diff --git a/packages/errors/package.json b/packages/errors/package.json
new file mode 100644
index 00000000..999bbc98
--- /dev/null
+++ b/packages/errors/package.json
@@ -0,0 +1,18 @@
+{
+  "name": "@bytelyst/errors",
+  "version": "0.1.0",
+  "type": "module",
+  "exports": {
+    ".": {
+      "import": "./dist/index.js",
+      "types": "./dist/index.d.ts"
+    }
+  },
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "files": ["dist"],
+  "scripts": {
+    "build": "tsc",
+    "test": "vitest run"
+  }
+}
diff --git a/packages/errors/src/__tests__/errors.test.ts b/packages/errors/src/__tests__/errors.test.ts
new file mode 100644
index 00000000..ee5ee235
--- /dev/null
+++ b/packages/errors/src/__tests__/errors.test.ts
@@ -0,0 +1,56 @@
+import { describe, it, expect } from "vitest";
+import {
+  ServiceError,
+  BadRequestError,
+  UnauthorizedError,
+  ForbiddenError,
+  NotFoundError,
+  ConflictError,
+  TooManyRequestsError,
+} from "../index.js";
+
+describe("ServiceError", () => {
+  it("sets statusCode and message", () => {
+    const err = new ServiceError(500, "boom");
+    expect(err.statusCode).toBe(500);
+    expect(err.message).toBe("boom");
+    expect(err).toBeInstanceOf(Error);
+    expect(err).toBeInstanceOf(ServiceError);
+  });
+
+  it("supports optional details", () => {
+    const err = new ServiceError(500, "boom", { field: "name" });
+    expect(err.details).toEqual({ field: "name" });
+  });
+});
+
+describe("HTTP error classes", () => {
+  const cases: [string, new () => ServiceError, number, string][] = [
+    ["BadRequestError", BadRequestError, 400, "Bad request"],
+    ["UnauthorizedError", UnauthorizedError, 401, "Unauthorized"],
+    ["ForbiddenError", ForbiddenError, 403, "Forbidden"],
+    ["NotFoundError", NotFoundError, 404, "Not found"],
+    ["ConflictError", ConflictError, 409, "Conflict"],
+    ["TooManyRequestsError", TooManyRequestsError, 429, "Too many requests"],
+  ];
+
+  for (const [name, Ctor, expectedStatus, expectedMessage] of cases) {
+    it(`${name} has status ${expectedStatus}`, () => {
+      const err = new Ctor();
+      expect(err.statusCode).toBe(expectedStatus);
+      expect(err.message).toBe(expectedMessage);
+      expect(err).toBeInstanceOf(ServiceError);
+    });
+  }
+
+  it("accepts custom message", () => {
+    const err = new NotFoundError("User not found");
+    expect(err.message).toBe("User not found");
+    expect(err.statusCode).toBe(404);
+  });
+
+  it("accepts details", () => {
+    const err = new TooManyRequestsError("Rate limited", { retryAfter: 60 });
+    expect(err.details).toEqual({ retryAfter: 60 });
+  });
+});
diff --git a/packages/errors/src/http-errors.ts b/packages/errors/src/http-errors.ts
new file mode 100644
index 00000000..7cae6b6a
--- /dev/null
+++ b/packages/errors/src/http-errors.ts
@@ -0,0 +1,37 @@
+import { ServiceError } from "./service-error.js";
+
+export class BadRequestError extends ServiceError {
+  constructor(message = "Bad request", details?: Record<string, unknown>) {
+    super(400, message, details);
+  }
+}
+
+export class UnauthorizedError extends ServiceError {
+  constructor(message = "Unauthorized", details?: Record<string, unknown>) {
+    super(401, message, details);
+  }
+}
+
+export class ForbiddenError extends ServiceError {
+  constructor(message = "Forbidden", details?: Record<string, unknown>) {
+    super(403, message, details);
+  }
+}
+
+export class NotFoundError extends ServiceError {
+  constructor(message = "Not found", details?: Record<string, unknown>) {
+    super(404, message, details);
+  }
+}
+
+export class ConflictError extends ServiceError {
+  constructor(message = "Conflict", details?: Record<string, unknown>) {
+    super(409, message, details);
+  }
+}
+
+export class TooManyRequestsError extends ServiceError {
+  constructor(message = "Too many requests", details?: Record<string, unknown>) {
+    super(429, message, details);
+  }
+}
diff --git a/packages/errors/src/index.ts b/packages/errors/src/index.ts
new file mode 100644
index 00000000..bb31685e
--- /dev/null
+++ b/packages/errors/src/index.ts
@@ -0,0 +1,9 @@
+export { ServiceError } from "./service-error.js";
+export {
+  BadRequestError,
+  UnauthorizedError,
+  ForbiddenError,
+  NotFoundError,
+  ConflictError,
+  TooManyRequestsError,
+} from "./http-errors.js";
diff --git a/packages/errors/src/service-error.ts b/packages/errors/src/service-error.ts
new file mode 100644
index 00000000..1d7b4bb7
--- /dev/null
+++ b/packages/errors/src/service-error.ts
@@ -0,0 +1,14 @@
+/**
+ * Base error class for typed HTTP service errors.
+ * All specific error types extend this class.
+ */
+export class ServiceError extends Error {
+  constructor(
+    public statusCode: number,
+    message: string,
+    public details?: Record<string, unknown>,
+  ) {
+    super(message);
+    this.name = "ServiceError";
+  }
+}
diff --git a/packages/errors/tsconfig.json b/packages/errors/tsconfig.json
new file mode 100644
index 00000000..5edad813
--- /dev/null
+++ b/packages/errors/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src"
+  },
+  "include": ["src"],
+  "exclude": ["src/**/*.test.ts"]
+}