diff --git a/packages/backend/package.json b/packages/backend/package.json
index c2b55b3..727b665 100644
--- a/packages/backend/package.json
+++ b/packages/backend/package.json
@@ -9,8 +9,10 @@
 	},
 	"dependencies": {
 		"@effect/schema": "catalog:",
+		"common": "workspace:^",
 		"effect": "catalog:",
 		"fast-check": "catalog:",
+		"make-api": "workspace:^",
 		"ulid": "catalog:"
 	}
 }
diff --git a/packages/backend/src/app.ts b/packages/backend/src/app.ts
index e43b297..4479e36 100644
--- a/packages/backend/src/app.ts
+++ b/packages/backend/src/app.ts
@@ -1,19 +1,28 @@
 import { Schema as S } from "@effect/schema";
-import { DateTime, Duration, Effect, Option as O, pipe } from "effect";
+import { DateTime, Duration, Either as E, Effect, Option as O, pipe } from "effect";
 import { RequestError } from "./RequestError";
 import { Database } from "./services/database";
 import { Request } from "./services/request";
-import { brotliCompress } from "node:zlib";
+import { Match } from "effect";
+import { Api } from "make-api";
+import { Login } from "common/api";
 import { AccessLog } from "common/db";
-import { LoginRequest, LoginResponse } from "common/api";
+import { brotliCompress } from "node:zlib";
 
-const match = (method: string, ...pattern: readonly string[]) => Effect.gen(function* () {
+const match = (api: Api.Api.Any) => Effect.gen(function* () {
 
 	const req = yield* Request;
 
-	return req.method === method
-		&& req.path.length === pattern.length
-		&& pattern.every((x, i) => x === "*" || x === req.path[i]);
+	return req.method === api.method
+		&& req.path.length === api.props.route.length
+		&& api.props.route.every((token, i) => pipe(
+			Match.value(token),
+			Match.tags({
+				Literal: ({ literal }) => req.path[i] === literal,
+				Param: ({ schema }) => E.isRight(S.decodeUnknownEither(schema)(req.path[i])),
+			}),
+			Match.exhaustive,
+		));
 });
 
 const WEIGHTED_TOKEN_REGEX = /^([!#$%'*+.^_`|~a-z0-9-])\s*(?:;\s*q=(0(?:\.[0-9]{0,3})?|1(?:\.0{0,3})?))?$/i;
@@ -81,23 +90,23 @@ export const app = pipe(
 
 		console.log(JSON.stringify(accessLog));
 
-		if (yield* match("POST", "login")) {
+		if (yield* match(Login)) {
 
-			const body = yield* requestJson(LoginRequest);
+			const body = yield* requestJson(Login.props.request.schema);
 
 			const user = yield* pipe(
 				db.getUserByUsername(body.username),
-				Effect.catchTag("NoSuchElementException", () => new RequestError({ status: 404, body: "Invalid username or password" })),
+				Effect.catchTag("NoSuchElementException", () => new RequestError({ status: 401, body: "Invalid username or password" })),
 			);
 
 			const valid = yield* Effect.promise(() => Bun.password.verify(body.password, user.password));
 			if (!valid) {
-				return yield* new RequestError({ status: 404, body: "Invalid username or password" });
+				return yield* new RequestError({ status: 401, body: "Invalid username or password" });
 			}
 
 			const sessionId = yield* db.createSession(user.userId);
 
-			const responseData = LoginResponse.make({
+			const responseData = Login.props.response[200].schema.make({
 				userId: user.userId,
 				username: user.username,
 				admin: user.admin,
@@ -105,7 +114,7 @@ export const app = pipe(
 
 			const responseJson = yield* pipe(
 				responseData,
-				S.encode(LoginResponse),
+				S.encode(Login.props.response[200].schema),
 				Effect.map(JSON.stringify),
 			);
 			const responseArray = new TextEncoder().encode(responseJson);
diff --git a/packages/backend/src/services/database.ts b/packages/backend/src/services/database.ts
index ca385b4..da44bef 100644
--- a/packages/backend/src/services/database.ts
+++ b/packages/backend/src/services/database.ts
@@ -1,6 +1,7 @@
 import { Schema as S } from "@effect/schema";
 import { Database as SqliteDatabase } from "bun:sqlite";
-import { SessionId, User, UserId } from "common";
+import { SessionId, UserId } from "common";
+import { User } from "common/db";
 import { Context, Effect, Layer, pipe } from "effect";
 import { NoSuchElementException } from "effect/Cause";
 
diff --git a/packages/backend/tsconfig.json b/packages/backend/tsconfig.json
index 4c3148f..292965e 100644
--- a/packages/backend/tsconfig.json
+++ b/packages/backend/tsconfig.json
@@ -5,5 +5,5 @@
 	},
 	"references": [
 		{ "path": "../common" },
-	]
+	],
 }
diff --git a/packages/common/package.json b/packages/common/package.json
index 00cae17..99792d6 100644
--- a/packages/common/package.json
+++ b/packages/common/package.json
@@ -3,12 +3,27 @@
 	"license": "UNLICENSED",
 	"private": true,
 	"type": "module",
+	"exports": {
+		".": {
+			"types": "./dist/index.d.ts",
+			"import": "./dist/index.js"
+		},
+		"./api": {
+			"types": "./dist/api.d.ts",
+			"import": "./dist/api.js"
+		},
+		"./db": {
+			"types": "./dist/db.d.ts",
+			"import": "./dist/db.js"
+		}
+	},
 	"devDependencies": {
 		"typescript": "catalog:"
 	},
 	"dependencies": {
 		"@effect/schema": "catalog:",
 		"effect": "catalog:",
-		"fast-check": "catalog:"
+		"fast-check": "catalog:",
+		"make-api": "workspace:^"
 	}
 }
diff --git a/packages/common/src/api.ts b/packages/common/src/api.ts
index 9a3e536..4cc6137 100644
--- a/packages/common/src/api.ts
+++ b/packages/common/src/api.ts
@@ -1,13 +1,19 @@
+import { Api } from "make-api";
 import { Schema as S } from "@effect/schema";
 import { UserId } from "common";
+import { pipe } from "effect";
 
-export const LoginRequest = S.Struct({
-	username: S.NonEmptyString,
-	password: S.NonEmptyString,
-});
-
-export const LoginResponse = S.Struct({
-	userId: UserId,
-	username: S.NonEmptyString,
-	admin: S.Boolean,
-});
+export const Login = pipe(
+	Api.make("POST", "login"),
+	Api.requestBodyJson(S.Struct({
+		username: S.NonEmptyString,
+		password: S.NonEmptyString,
+	})),
+	Api.responseBodyJson(200, S.Struct({
+		userId: UserId,
+		username: S.NonEmptyString,
+		admin: S.Boolean,
+	})),
+	Api.responseBodyText(400, S.String),
+	Api.responseBodyText(401, S.String),
+);
diff --git a/packages/common/tsconfig.json b/packages/common/tsconfig.json
index f52a4d1..bf9b8f8 100644
--- a/packages/common/tsconfig.json
+++ b/packages/common/tsconfig.json
@@ -1,3 +1,6 @@
 {
 	"extends": "../../tsconfig.base.json",
+	"references": [
+		{ "path": "../make-api" },
+	],
 }
diff --git a/packages/frontend/package.json b/packages/frontend/package.json
index c188506..1872cff 100644
--- a/packages/frontend/package.json
+++ b/packages/frontend/package.json
@@ -11,8 +11,10 @@
 	},
 	"dependencies": {
 		"@effect/schema": "catalog:",
+		"common": "workspace:^",
 		"effect": "catalog:",
 		"fast-check": "catalog:",
+		"make-api": "workspace:^",
 		"preact": "catalog:",
 		"preact-iso": "catalog:"
 	}
diff --git a/packages/frontend/src/routes/Login.tsx b/packages/frontend/src/routes/Login.tsx
index bec7f9f..50f4809 100644
--- a/packages/frontend/src/routes/Login.tsx
+++ b/packages/frontend/src/routes/Login.tsx
@@ -1,9 +1,9 @@
 import { Schema as S } from "@effect/schema";
-import { LoginRequest, LoginResponse } from "common/api";
+import { Login } from "common/api";
 import { useId, useMemo, useRef } from "preact/hooks";
 import { useStore } from "../store";
 import * as style from "./Login.css";
-import { Effect, Fiber, pipe } from "effect";
+import { Effect, Fiber, Option as O, pipe } from "effect";
 
 export default () => {
 
@@ -13,16 +13,18 @@ export default () => {
 	const setLoginUsername = useStore(state => state.setLoginUsername);
 	const setLoginPassword = useStore(state => state.setLoginPassword);
 
+	const setUser = useStore(state => state.setUser);
+
 	const usernameId = useId();
 	const passwordId = useId();
 
 	const requestFiber = useRef<Fiber.RuntimeFiber<void> | null>(null);
 	const requestEffect = useMemo(() => Effect.gen(function* () {
-		const requestData = LoginRequest.make(LoginRequest.make({ username: loginUsername, password: loginPassword }));
+		const requestData = Login.props.request.schema.make({ username: loginUsername, password: loginPassword });
 
 		const requestJson = yield* pipe(
 			requestData,
-			S.encode(LoginRequest),
+			S.encode(Login.props.request.schema),
 			Effect.map(JSON.stringify),
 			Effect.orDie,
 		);
@@ -40,12 +42,13 @@ export default () => {
 
 		const responseData = yield* pipe(
 			Effect.promise(() => res.json()),
-			Effect.flatMap(S.decodeUnknown(LoginResponse)),
+			Effect.flatMap(S.decodeUnknown(Login.props.response[200].schema)),
 			Effect.orDie,
 		);
 
 		setLoginUsername("");
 		setLoginPassword("");
+		setUser(O.some(responseData));
 
 		const a = document.createElement("a");
 		a.href = "/";
diff --git a/packages/frontend/src/store.ts b/packages/frontend/src/store.ts
index 7306f71..eb0b3fe 100644
--- a/packages/frontend/src/store.ts
+++ b/packages/frontend/src/store.ts
@@ -1,23 +1,44 @@
-import { identity } from "effect";
+import { UserId } from "common";
+import { identity, Option as O } from "effect";
 import { useLayoutEffect, useState } from "preact/hooks";
 
 export type Update<T> = T | ((prev: T) => T);
 export type Updater<T> = (action: Update<T>) => void;
 
+export const mapProp = <const K extends string, T>(prop: K, action: T) => <O extends { readonly [_ in K]: T }>(object: O): O => {
+	return Object.freeze({ ...object, [prop]: typeof action === "function" ? action(object[prop]) : action });
+};
+
+export namespace Store {
+	export interface User {
+		readonly username: string;
+		readonly userId: UserId;
+		readonly admin: boolean;
+	}
+}
+
 export interface Store {
 	readonly loginUsername: string;
 	readonly loginPassword: string;
 
+	readonly user: O.Option<Store.User>;
+
 	readonly setLoginUsername: Updater<string>;
 	readonly setLoginPassword: Updater<string>;
+
+	readonly setUser: Updater<O.Option<Store.User>>;
 }
 
 let store: Store = Object.freeze<Store>({
 	loginUsername: "",
 	loginPassword: "",
 
-	setLoginUsername: (action) => set(({ loginUsername }) => ({ loginUsername: typeof action === "function" ? action(loginUsername) : loginUsername })),
-	setLoginPassword: (action) => set(({ loginPassword }) => ({ loginPassword: typeof action === "function" ? action(loginPassword) : loginPassword })),
+	user: O.none(),
+
+	setLoginUsername: (action) => set(mapProp("loginUsername", action)),
+	setLoginPassword: (action) => set(mapProp("loginPassword", action)),
+
+	setUser: (action) => set(mapProp("user", action)),
 });
 
 // --- STORE IMPLEMENTATION ----------------------------------------------------
diff --git a/packages/frontend/tsconfig.json b/packages/frontend/tsconfig.json
index 6157f4a..c71ee5d 100644
--- a/packages/frontend/tsconfig.json
+++ b/packages/frontend/tsconfig.json
@@ -2,5 +2,5 @@
 	"extends": "../../tsconfig.base.json",
 	"references": [
 		{ "path": "../common" },
-	]
+	],
 }
diff --git a/packages/make-api/package.json b/packages/make-api/package.json
new file mode 100644
index 0000000..01a7e88
--- /dev/null
+++ b/packages/make-api/package.json
@@ -0,0 +1,20 @@
+{
+	"name": "make-api",
+	"license": "UNLICENSED",
+	"private": true,
+	"type": "module",
+	"exports": {
+		".": {
+			"types": "./dist/index.d.ts",
+			"import": "./dist/index.js"
+		}
+	},
+	"devDependencies": {
+		"typescript": "catalog:"
+	},
+	"dependencies": {
+		"@effect/schema": "catalog:",
+		"effect": "catalog:",
+		"fast-check": "catalog:"
+	}
+}
diff --git a/packages/make-api/src/Api.ts b/packages/make-api/src/Api.ts
new file mode 100644
index 0000000..1133078
--- /dev/null
+++ b/packages/make-api/src/Api.ts
@@ -0,0 +1,142 @@
+import { Schema as S } from "@effect/schema";
+import type { Field } from "./Field";
+import type { Method } from "./Method";
+import type { MimeTypePredicate } from "./MimeType";
+import { QueryEmpty, type Query } from "./Query";
+import { RequestBodyFile, RequestBodyJson, RequestBodyMultipart, RequestBodyNone, RequestBodyText, RequestBodyUrlEncoded, type RequestBody } from "./RequestBody";
+import { ResponseBodyFile, ResponseBodyJson, ResponseBodyText, ResponseEmpty, type ResponseBody } from "./ResponseBody";
+import { Route, RouteLiteral, RouteParam } from "./Route";
+
+export interface Api<Props extends Api.PropsAny> {
+	readonly method: Method;
+	readonly props: Props;
+}
+
+export namespace Api {
+	export type Any = Api<PropsAny>;
+
+	export type Props<T extends Api.Any> = T extends Api<infer Props> ? Props : never;
+
+	export type PropsAny = {
+		readonly route: Route.Any;
+		readonly request: RequestBody.Any;
+		readonly response: { readonly [_: number]: ResponseBody.Any };
+		readonly query: Query.Any;
+	};
+}
+
+export const Api = <const Props extends Api.PropsAny>(method: Method, props: Props): Api<Props> => Object.freeze<Api<Props>>({
+	method,
+	props,
+});
+
+// --- BUILDERS ----------------------------------------------------------------
+
+export type RouteInputLiteral<Literal extends string> = Literal;
+
+export type RouteInputParam<Name extends string, Schema extends S.Schema<any, string>> = readonly [Name, Schema];
+
+export namespace RouteInputLiteral {
+	export type Any = RouteInputLiteral<string>;
+}
+
+export namespace RouteInputParam {
+	export type Any = RouteInputParam<string, S.Schema<any, string>>;
+}
+
+export namespace RouteInput {
+	export type Any = readonly (
+		| RouteInputLiteral.Any
+		| RouteInputParam.Any
+	)[];
+
+	export type Route<R extends RouteInput.Any> = { readonly [K in keyof R]:
+		R[K] extends RouteInputLiteral<infer Literal> ? RouteLiteral<Literal>
+		: R[K] extends RouteInputParam<infer Name, infer Schema> ? RouteParam<Name, Schema>
+		: never;
+	};
+}
+
+export const make = <const R extends RouteInput.Any>(method: Method, ...routeInput: R): Api<{
+	readonly route: RouteInput.Route<R>,
+	readonly request: RequestBodyNone,
+	readonly response: {},
+	readonly query: {},
+}> => Api(method, {
+	route: Route(...routeInput.map((r) => typeof r === "string" ? RouteLiteral(r) : RouteParam(r[0], r[1])) as RouteInput.Route<R>),
+	request: RequestBodyNone,
+	response: ResponseEmpty,
+	query: QueryEmpty,
+});
+
+export const requestBodyText = <const Schema extends S.Schema<any, string>>(schema: Schema) =>
+	<const T extends Api.Any>({ method, props }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: RequestBodyText<Schema>,
+		readonly response: T["props"]["response"],
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, request: RequestBodyText(schema) });
+
+export const requestBodyJson = <const Schema extends S.Schema.Any>(schema: Schema) =>
+	<const T extends Api.Any>({ method, props }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: RequestBodyJson<Schema>,
+		readonly response: T["props"]["response"],
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, request: RequestBodyJson(schema) });
+
+export const requestBodyUrlEncoded = <const Fields extends { readonly [_: string]: Field.AnyUrlEncoded }>(fields: Fields) =>
+	<const T extends Api.Any>({ method, props }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: RequestBodyUrlEncoded<Fields>,
+		readonly response: T["props"]["response"],
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, request: RequestBodyUrlEncoded(fields) });
+
+export const requestBodyMultipart = <const Fields extends { readonly [_: string]: Field.Any }>(fields: Fields) =>
+	<const T extends Api.Any>({ method, props }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: RequestBodyMultipart<Fields>,
+		readonly response: T["props"]["response"],
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, request: RequestBodyMultipart(fields) });
+
+export const requestBodyFile = <const MimeType extends string>(mimeType: MimeTypePredicate<MimeType>) =>
+	<const T extends Api.Any>({ method, props }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: RequestBodyFile<MimeType>,
+		readonly response: T["props"]["response"],
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, request: RequestBodyFile(mimeType) });
+
+export const responseBodyText = <const Status extends number, const Schema extends S.Schema<any, string>>(status: Status, schema: Schema) =>
+	<const T extends Api.Any>({ method, props: { response, ...props } }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: T["props"]["request"],
+		readonly response: { readonly [K in keyof T["props"]["response"] | Status]: K extends Status ? ResponseBodyText<Schema> : T["props"]["response"][K] },
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, response: Object.freeze<any>({ ...response, [status]: ResponseBodyText(schema) }) });
+
+export const responseBodyJson = <const Status extends number, const Schema extends S.Schema.Any>(status: Status, schema: Schema) =>
+	<const T extends Api.Any>({ method, props: { response, ...props } }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: T["props"]["request"],
+		readonly response: { readonly [K in keyof T["props"]["response"] | Status]: K extends Status ? ResponseBodyJson<Schema> : T["props"]["response"][K] },
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, response: Object.freeze<any>({ ...response, [status]: ResponseBodyJson(schema) }) });
+
+export const responseBodyFile = <const Status extends number, const MimeType extends string>(status: Status, mimeType: MimeTypePredicate<MimeType>) =>
+	<const T extends Api.Any>({ method, props: { response, ...props } }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: T["props"]["request"],
+		readonly response: { readonly [K in keyof T["props"]["response"] | Status]: K extends Status ? ResponseBodyFile<MimeType> : T["props"]["response"][K] },
+		readonly query: T["props"]["query"],
+	}> => Api(method, { ...props, response: Object.freeze<any>({ ...response, [status]: ResponseBodyFile(mimeType) }) });
+
+export const query = <const Query extends Query.Any>(query: Query) =>
+	<const T extends Api.Any>({ method, props: { query: _, ...props } }: T): Api<{
+		readonly route: T["props"]["route"],
+		readonly request: T["props"]["request"],
+		readonly response: T["props"]["response"],
+		readonly query: Query,
+	}> => Api(method, { ...props, query });
diff --git a/packages/make-api/src/Field.ts b/packages/make-api/src/Field.ts
new file mode 100644
index 0000000..63f0856
--- /dev/null
+++ b/packages/make-api/src/Field.ts
@@ -0,0 +1,68 @@
+import { Schema as S } from "@effect/schema";
+import type { MimeTypePredicate } from "./MimeType";
+import type { Multiplicity } from "./Multiplicity";
+
+// --- INTERFACES --------------------------------------------------------------
+
+export interface FieldText<M extends Multiplicity, Schema extends S.Schema<any, string>> {
+	readonly _tag: "Text";
+	readonly multiplicity: M;
+	readonly schema: Schema;
+}
+
+export interface FieldJson<M extends Multiplicity, Schema extends S.Schema.Any> {
+	readonly _tag: "Json";
+	readonly multiplicity: M;
+	readonly schema: Schema;
+}
+
+export interface FieldFile<M extends Multiplicity, MimeType extends string> {
+	readonly _tag: "File";
+	readonly multiplicity: M;
+	readonly mimeType: MimeTypePredicate<MimeType>;
+}
+
+export namespace FieldText {
+	export type Any = FieldText<Multiplicity, S.Schema<any, string>>;
+}
+
+export namespace FieldJson {
+	export type Any = FieldJson<Multiplicity, S.Schema.Any>;
+}
+
+export namespace FieldFile {
+	export type Any = FieldFile<Multiplicity, string>;
+}
+
+export namespace Field {
+	export type Any =
+		| FieldText.Any
+		| FieldJson.Any
+		| FieldFile.Any
+		;
+
+	export type AnyUrlEncoded =
+		| FieldText.Any
+		| FieldJson.Any
+		;
+}
+
+// --- CONSTRUCTORS ------------------------------------------------------------
+
+export const FieldText = <const M extends Multiplicity, const Schema extends S.Schema<any, string>>(multiplicity: M, schema: Schema): FieldText<M, Schema> => Object.freeze<FieldText<M, Schema>>({
+	_tag: "Text",
+	multiplicity,
+	schema,
+});
+
+export const FieldJson = <const M extends Multiplicity, const Schema extends S.Schema.Any>(multiplicity: M, schema: Schema): FieldJson<M, Schema> => Object.freeze<FieldJson<M, Schema>>({
+	_tag: "Json",
+	multiplicity,
+	schema,
+});
+
+export const FieldFile = <const M extends Multiplicity, const MimeType extends string>(multiplicity: M, mimeType: MimeTypePredicate<MimeType>): FieldFile<M, MimeType> => Object.freeze<FieldFile<M, MimeType>>({
+	_tag: "File",
+	multiplicity,
+	mimeType,
+});
diff --git a/packages/make-api/src/Method.ts b/packages/make-api/src/Method.ts
new file mode 100644
index 0000000..ffad978
--- /dev/null
+++ b/packages/make-api/src/Method.ts
@@ -0,0 +1,7 @@
+export type Method =
+	| "GET"
+	| "POST"
+	| "PUT"
+	| "DELETE"
+	| "PATCH"
+	;
diff --git a/packages/make-api/src/MimeType.ts b/packages/make-api/src/MimeType.ts
new file mode 100644
index 0000000..c18b2fe
--- /dev/null
+++ b/packages/make-api/src/MimeType.ts
@@ -0,0 +1,3 @@
+import { Predicate } from "effect"
+
+export type MimeTypePredicate<T extends string> = T | readonly T[] | Predicate.Refinement<string, T>;
diff --git a/packages/make-api/src/Multiplicity.ts b/packages/make-api/src/Multiplicity.ts
new file mode 100644
index 0000000..ff37349
--- /dev/null
+++ b/packages/make-api/src/Multiplicity.ts
@@ -0,0 +1,17 @@
+import type { Option as O } from "effect";
+
+export type Multiplicity =
+	| "single"
+	| "optional"
+	| "multiple"
+	| "any"
+	;
+
+export namespace Multiplicity {
+	export type With<M extends Multiplicity, T> = {
+		single: T,
+		optional: O.Option<T>,
+		multiple: readonly [T, ...T[]],
+		any: readonly T[],
+	}[M];
+}
diff --git a/packages/make-api/src/Query.ts b/packages/make-api/src/Query.ts
new file mode 100644
index 0000000..7b9571c
--- /dev/null
+++ b/packages/make-api/src/Query.ts
@@ -0,0 +1,7 @@
+import type { Field } from "./Field";
+
+export namespace Query {
+	export type Any = { readonly [_: string]: Field.AnyUrlEncoded };
+}
+
+export const QueryEmpty: {} = Object.freeze<{}>({});
diff --git a/packages/make-api/src/RequestBody.ts b/packages/make-api/src/RequestBody.ts
new file mode 100644
index 0000000..baaf6d3
--- /dev/null
+++ b/packages/make-api/src/RequestBody.ts
@@ -0,0 +1,96 @@
+import { Schema as S } from "@effect/schema";
+import type { Field } from "./Field";
+import type { MimeTypePredicate } from "./MimeType";
+
+// --- INTERFACES --------------------------------------------------------------
+
+export interface RequestBodyNone {
+	readonly _tag: "None";
+}
+
+export interface RequestBodyText<Schema extends S.Schema<any, string>> {
+	readonly _tag: "Text";
+	readonly schema: Schema;
+}
+
+export interface RequestBodyJson<Schema extends S.Schema.Any> {
+	readonly _tag: "Json";
+	readonly schema: Schema;
+}
+
+export interface RequestBodyUrlEncoded<Fields extends { readonly [_: string]: Field.AnyUrlEncoded }> {
+	readonly _tag: "UrlEncoded";
+	readonly fields: Readonly<Fields>;
+}
+
+export interface RequestBodyMultipart<Fields extends { readonly [_: string]: Field.Any }> {
+	readonly _tag: "Multipart";
+	readonly fields: Readonly<Fields>;
+}
+
+export interface RequestBodyFile<MimeType extends string> {
+	readonly _tag: "File";
+	readonly mimeType: MimeTypePredicate<MimeType>;
+}
+
+export namespace RequestBodyText {
+	export type Any = RequestBodyText<S.Schema<any, string>>;
+}
+
+export namespace RequestBodyJson {
+	export type Any = RequestBodyJson<S.Schema.Any>;
+}
+
+export namespace RequestBodyUrlEncoded {
+	export type Any = RequestBodyUrlEncoded<{}>;
+}
+
+export namespace RequestBodyMultipart {
+	export type Any = RequestBodyMultipart<{}>;
+}
+
+export namespace RequestBodyFile {
+	export type Any = RequestBodyFile<string>;
+}
+
+export namespace RequestBody {
+	export type Any =
+		| RequestBodyNone
+		| RequestBodyText.Any
+		| RequestBodyJson.Any
+		| RequestBodyUrlEncoded.Any
+		| RequestBodyMultipart.Any
+		| RequestBodyFile.Any
+		;
+}
+
+// --- CONSTRUCTORS ------------------------------------------------------------
+
+export const RequestBodyNone: RequestBodyNone = Object.freeze<RequestBodyNone>({
+	_tag: "None",
+});
+
+export const RequestBodyText = <const Schema extends S.Schema<any, string>>(schema: Schema): RequestBodyText<Schema> => Object.freeze<RequestBodyText<Schema>>({
+	_tag: "Text",
+	schema,
+});
+
+export const RequestBodyJson = <const Schema extends S.Schema.Any>(schema: Schema): RequestBodyJson<Schema> => Object.freeze<RequestBodyJson<Schema>>({
+	_tag: "Json",
+	schema,
+});
+
+export const RequestBodyUrlEncoded = <const Fields extends { readonly [_: string]: Field.AnyUrlEncoded }>(fields: Fields): RequestBodyUrlEncoded<Fields> => Object.freeze<RequestBodyUrlEncoded<Fields>>({
+	_tag: "UrlEncoded",
+	fields,
+});
+
+export const RequestBodyMultipart = <const Fields extends { readonly [_: string]: Field.Any }>(fields: Fields): RequestBodyMultipart<Fields> => Object.freeze<RequestBodyMultipart<Fields>>({
+	_tag: "Multipart",
+	fields,
+});
+
+export const RequestBodyFile = <const MimeType extends string>(mimeType: MimeTypePredicate<MimeType>): RequestBodyFile<MimeType> => Object.freeze<RequestBodyFile<MimeType>>({
+	_tag: "File",
+	mimeType,
+});
diff --git a/packages/make-api/src/ResponseBody.ts b/packages/make-api/src/ResponseBody.ts
new file mode 100644
index 0000000..6e4b21e
--- /dev/null
+++ b/packages/make-api/src/ResponseBody.ts
@@ -0,0 +1,67 @@
+import { Schema as S } from "@effect/schema";
+import type { MimeTypePredicate } from "./MimeType";
+
+// --- INTERFACES --------------------------------------------------------------
+
+export interface ResponseBodyNone {
+	readonly _tag: "None";
+}
+
+export interface ResponseBodyText<Schema extends S.Schema<any, string>> {
+	readonly _tag: "Text";
+	readonly schema: Schema;
+}
+
+export interface ResponseBodyJson<Schema extends S.Schema.Any> {
+	readonly _tag: "Json";
+	readonly schema: Schema;
+}
+
+export interface ResponseBodyFile<MimeType extends string> {
+	readonly _tag: "File";
+	readonly mimeType: MimeTypePredicate<MimeType>;
+}
+
+export namespace ResponseBodyText {
+	export type Any = ResponseBodyText<S.Schema<any, string>>;
+}
+
+export namespace ResponseBodyJson {
+	export type Any = ResponseBodyJson<S.Schema.Any>;
+}
+
+export namespace ResponseBodyFile {
+	export type Any = ResponseBodyFile<string>;
+}
+
+export namespace ResponseBody {
+	export type Any =
+		| ResponseBodyNone
+		| ResponseBodyText.Any
+		| ResponseBodyJson.Any
+		| ResponseBodyFile.Any
+		;
+}
+
+// --- CONSTRUCTORS ------------------------------------------------------------
+
+export const ResponseBodyNone: ResponseBodyNone = Object.freeze<ResponseBodyNone>({
+	_tag: "None",
+});
+
+export const ResponseBodyText = <const Schema extends S.Schema<any, string>>(schema: Schema): ResponseBodyText<Schema> => Object.freeze<ResponseBodyText<Schema>>({
+	_tag: "Text",
+	schema,
+});
+
+export const ResponseBodyJson = <const Schema extends S.Schema.Any>(schema: Schema): ResponseBodyJson<Schema> => Object.freeze<ResponseBodyJson<Schema>>({
+	_tag: "Json",
+	schema,
+});
+
+export const ResponseBodyFile = <const MimeType extends string>(mimeType: MimeTypePredicate<MimeType>): ResponseBodyFile<MimeType> => Object.freeze<ResponseBodyFile<MimeType>>({
+	_tag: "File",
+	mimeType,
+});
+
+export const ResponseEmpty: {} = Object.freeze<{}>({});
diff --git a/packages/make-api/src/Route.ts b/packages/make-api/src/Route.ts
new file mode 100644
index 0000000..4b87dbb
--- /dev/null
+++ b/packages/make-api/src/Route.ts
@@ -0,0 +1,44 @@
+import { Schema as S } from "@effect/schema";
+
+// --- INTERFACES --------------------------------------------------------------
+
+export interface RouteLiteral<Literal extends string> {
+	readonly _tag: "Literal";
+	readonly literal: Literal;
+}
+
+export interface RouteParam<Name extends string, Schema extends S.Schema<any, string>> {
+	readonly _tag: "Param";
+	readonly name: Name;
+	readonly schema: Schema;
+}
+
+export namespace RouteLiteral {
+	export type Any = RouteLiteral<string>;
+}
+
+export namespace RouteParam {
+	export type Any = RouteParam<string, S.Schema<any, string>>;
+}
+
+export namespace Route {
+	export type Any = readonly (
+		| RouteLiteral.Any
+		| RouteParam.Any
+	)[];
+}
+
+// --- CONSTRUCTORS ------------------------------------------------------------
+
+export const RouteLiteral = <const Literal extends string>(literal: Literal): RouteLiteral<Literal> => Object.freeze<RouteLiteral<Literal>>({
+	_tag: "Literal",
+	literal,
+});
+
+export const RouteParam = <const Name extends string, const Schema extends S.Schema<any, string>>(name: Name, schema: Schema): RouteParam<Name, Schema> => Object.freeze<RouteParam<Name, Schema>>({
+	_tag: "Param",
+	name,
+	schema,
+});
+
+export const Route = <const Route extends Route.Any>(...route: Route): Route => Object.freeze<Route>(route);
diff --git a/packages/make-api/src/index.ts b/packages/make-api/src/index.ts
new file mode 100644
index 0000000..f200a36
--- /dev/null
+++ b/packages/make-api/src/index.ts
@@ -0,0 +1,9 @@
+export * as Api from "./Api";
+export * from "./Field";
+export * from "./Method";
+export * from "./MimeType";
+export * from "./Multiplicity";
+export * from "./Query";
+export * from "./RequestBody";
+export * from "./ResponseBody";
+export * from "./Route";
diff --git a/packages/make-api/tsconfig.json b/packages/make-api/tsconfig.json
new file mode 100644
index 0000000..f52a4d1
--- /dev/null
+++ b/packages/make-api/tsconfig.json
@@ -0,0 +1,3 @@
+{
+	"extends": "../../tsconfig.base.json",
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0e0bc32..0cee2cd 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -50,12 +50,18 @@ importers:
       '@effect/schema':
         specifier: 'catalog:'
         version: 0.70.1(effect@3.6.0)
+      common:
+        specifier: workspace:^
+        version: link:../common
       effect:
         specifier: 'catalog:'
         version: 3.6.0
       fast-check:
         specifier: 'catalog:'
         version: 3.20.0
+      make-api:
+        specifier: workspace:^
+        version: link:../make-api
       ulid:
         specifier: 'catalog:'
         version: 2.3.0
@@ -78,6 +84,9 @@ importers:
       fast-check:
         specifier: 'catalog:'
         version: 3.20.0
+      make-api:
+        specifier: workspace:^
+        version: link:../make-api
     devDependencies:
       typescript:
         specifier: 'catalog:'
@@ -88,12 +97,18 @@ importers:
       '@effect/schema':
         specifier: 'catalog:'
         version: 0.70.1(effect@3.6.0)
+      common:
+        specifier: workspace:^
+        version: link:../common
       effect:
         specifier: 'catalog:'
         version: 3.6.0
       fast-check:
         specifier: 'catalog:'
         version: 3.20.0
+      make-api:
+        specifier: workspace:^
+        version: link:../make-api
       preact:
         specifier: 'catalog:'
         version: 10.23.1
@@ -114,6 +129,22 @@ importers:
         specifier: 'catalog:'
         version: 5.3.5(@types/node@20.12.14)
 
+  packages/make-api:
+    dependencies:
+      '@effect/schema':
+        specifier: 'catalog:'
+        version: 0.70.1(effect@3.6.0)
+      effect:
+        specifier: 'catalog:'
+        version: 3.6.0
+      fast-check:
+        specifier: 'catalog:'
+        version: 3.20.0
+    devDependencies:
+      typescript:
+        specifier: 'catalog:'
+        version: 5.6.0-dev.20240802
+
 packages:
 
   '@ampproject/remapping@2.3.0':
diff --git a/tsconfig.base.json b/tsconfig.base.json
index 49fb7d0..e267ed8 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -30,6 +30,7 @@
 			"common": ["./packages/common/src/index.ts"],
 			"common/api": ["./packages/common/src/api.ts"],
 			"common/db": ["./packages/common/src/db.ts"],
+			"make-api": ["./packages/make-api/index.ts"],
 		},
 	},
 	"include": ["${configDir}/src"],
diff --git a/tsconfig.json b/tsconfig.json
index d02120e..97e426b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,5 +5,6 @@
 		{ "path": "packages/backend" },
 		{ "path": "packages/common" },
 		{ "path": "packages/frontend" },
+		{ "path": "packages/make-api" },
 	],
 }