/convex-http-actions

Convex HTTP actions

Defines public HTTP endpoints served from the deployment's .convex.site domain. The one rule: an httpAction handler treats every byte of the request as untrusted, verifies it, then calls internal.* functions with ctx.runQuery or ctx.runMutation. It never reads or writes ctx.db directly.

When to reach for this

• A third party (Stripe, Clerk, Resend, GitHub) needs a URL to POST events to
• A client without the Convex SDK (mobile app, CLI, another backend) needs a plain HTTP API
• A browser needs to download or stream bytes without going through useQuery
• A script or form needs to upload bytes over HTTP instead of an upload URL

httpAction or mutation

HTTP actions get no argument validators and no automatic auth. They run in the default Convex runtime, so Web APIs (fetch, crypto.subtle, Response, ReadableStream) work without "use node". Request and response bodies are capped at 20MB.

Router skeleton

The router must live at convex/http.ts and be the default export. A router in any other file is ignored.

// convex/http.ts
import { httpRouter } from "convex/server";
import { httpAction } from "./_generated/server";
import { internal } from "./_generated/api";

const http = httpRouter();

http.route({
  path: "/api/items",
  method: "POST",
  handler: httpAction(async (ctx, request) => {
    let body: { name?: unknown };
    try {
      body = await request.json();
    } catch {
      return json({ error: "Invalid JSON body" }, 400);
    }
    if (typeof body.name !== "string") {
      return json({ error: "name is required" }, 400);
    }
    const id = await ctx.runMutation(internal.items.create, { name: body.name });
    return json({ id }, 201);
  }),
});

export default http;

// JSON response helper shared by every route in this file
function json(data: unknown, status = 200): Response {
  return new Response(JSON.stringify(data), {
    status,
    headers: { "Content-Type": "application/json" },
  });
}

The endpoint is reachable at https://<deployment>.convex.site/api/items. Note .convex.site, not .convex.cloud. path matches exactly; use pathPrefix: "/api/items/" for dynamic segments and read the tail from new URL(request.url).pathname.

Calling queries and mutations from the handler

ctx.runQuery, ctx.runMutation, ctx.runAction, ctx.storage, ctx.scheduler, and ctx.auth are all available inside httpAction. Point them at internal.* functions so database logic is not also exposed as a public Convex function. Arguments still pass through the target's validators, so a bad shape fails there with a clear error.

// convex/items.ts
import { internalMutation } from "./_generated/server";
import { v } from "convex/values";

export const create = internalMutation({
  args: { name: v.string() },
  returns: v.id("items"),
  handler: async (ctx, args) => {
    return await ctx.db.insert("items", { name: args.name });
  },
});

For slow work (sending email, calling an LLM), respond 200 right away and hand off with ctx.scheduler.runAfter(0, internal.jobs.process, args). Providers time out and retry if the handler stalls.

Webhook with signature verification

Read the raw body once with request.text(). Parsing first changes the bytes and breaks the signature. This generic HMAC SHA-256 pattern covers most providers; Stripe, Clerk, and Resend specifics are in the reference below.

// convex/http.ts (add to the router above)
http.route({
  path: "/webhooks/provider",
  method: "POST",
  handler: httpAction(async (ctx, request) => {
    const signature = request.headers.get("x-signature");
    if (!signature) return new Response("Missing signature", { status: 400 });

    const raw = await request.text();
    const secret = process.env.PROVIDER_WEBHOOK_SECRET;
    if (!secret) return new Response("Webhook secret not configured", { status: 500 });
    if (!(await verifyHmac(raw, signature, secret))) {
      return new Response("Invalid signature", { status: 401 });
    }

    const event = JSON.parse(raw) as { id: string; type: string; data: unknown };
    // The mutation returns early if this event id was already processed.
    await ctx.runMutation(internal.webhooks.record, {
      source: "provider",
      eventId: event.id,
      type: event.type,
      payload: event.data,
    });
    return new Response(null, { status: 200 });
  }),
});

async function verifyHmac(payload: string, signature: string, secret: string): Promise<boolean> {
  const enc = new TextEncoder();
  const key = await crypto.subtle.importKey(
    "raw",
    enc.encode(secret),
    { name: "HMAC", hash: "SHA-256" },
    false,
    ["sign"],
  );
  const mac = await crypto.subtle.sign("HMAC", key, enc.encode(payload));
  const expected = Array.from(new Uint8Array(mac))
    .map((b) => b.toString(16).padStart(2, "0"))
    .join("");
  return safeEqual(expected, signature);
}

// Constant time compare so response timing does not leak the signature
function safeEqual(a: string, b: string): boolean {
  if (a.length !== b.length) return false;
  let diff = 0;
  for (let i = 0; i < a.length; i++) diff |= a.charCodeAt(i) ^ b.charCodeAt(i);
  return diff === 0;
}

Providers retry on any non 2xx and sometimes on network flakes, so the same event arrives more than once. Deduplicate by event id inside the mutation, which is a transaction:

// convex/webhooks.ts
import { internalMutation } from "./_generated/server";
import { v } from "convex/values";

export const record = internalMutation({
  args: { source: v.string(), eventId: v.string(), type: v.string(), payload: v.any() },
  returns: v.null(),
  handler: async (ctx, args) => {
    const seen = await ctx.db
      .query("webhookEvents")
      .withIndex("by_source_and_event_id", (q) =>
        q.eq("source", args.source).eq("eventId", args.eventId),
      )
      .unique();
    if (seen) return null;
    await ctx.db.insert("webhookEvents", args);
    // Apply the event's side effects here, in the same transaction.
    return null;
  },
});

Schema: webhookEvents: defineTable({ source: v.string(), eventId: v.string(), type: v.string(), payload: v.any() }).index("by_source_and_event_id", ["source", "eventId"]).

Open references/webhooks.md for Stripe (constructEvent in a Node action), Clerk and Resend (svix headers), replay protection with timestamps, and a fuller idempotency table with status tracking.

CORS, path params, auth headers, streaming, files

Browsers send an OPTIONS preflight before cross origin POSTs, so each browser facing path needs an OPTIONS route returning the same Access-Control-* headers as the real route. Bearer tokens from your configured auth provider are read with await ctx.auth.getUserIdentity(), the same call used in queries. Streaming works by returning new Response(readableStream), and files are served with ctx.storage.get(storageId) or accepted with request.blob() then ctx.storage.store(blob).

Open references/rest-and-cors.md when building a REST style API: path parameters and id validation, the CORS preflight pair, JSON error conventions, bearer and API key auth, streaming responses, and file upload and download routes.

Common mistakes

Checklist

• Router is at convex/http.ts and exported as default
• Every route parses the body inside try/catch and returns 400 on bad input
• Handlers call internal.* functions, never ctx.db
• Webhook routes read request.text() once and verify the signature before parsing
• Webhook secrets come from process.env and are set in the deployment, not hardcoded
• Events are deduplicated by provider event id inside a mutation
• Slow work is scheduled, and the handler returns 2xx quickly
• Browser called routes have a matching OPTIONS route
• The provider dashboard points at the .convex.site URL
• JSON responses set Content-Type: application/json

Docs

• https://docs.convex.dev/llms.txt
• https://docs.convex.dev/functions/http-actions
• https://docs.convex.dev/auth/clerk
• https://docs.convex.dev/file-storage/serve-files