Reddit

Lightweight, dependency-free, in-memory fake of the Reddit API for testing code that authenticates, reads listings, and submits posts.

Default port: 4804

Quick start

import { RedditServer } from "./services/reddit/src/server.js";

const server = new RedditServer(4804);
await server.start();
// ... run your app/tests ...
await server.stop();

Point your client (or raw fetch) at http://127.0.0.1:4804. First obtain a token, then call OAuth endpoints with a Bearer token and a unique User-Agent header (Reddit enforces this):

const token = await fetch("http://127.0.0.1:4804/api/v1/access_token", {
  method: "POST",
  headers: {
    Authorization: "Basic " + Buffer.from("clientId:secret").toString("base64"),
    "Content-Type": "application/x-www-form-urlencoded",
  },
  body: "grant_type=client_credentials",
}).then((r) => r.json());

const me = await fetch("http://127.0.0.1:4804/api/v1/me", {
  headers: { Authorization: `Bearer ${token.access_token}`, "User-Agent": "myapp/1.0 (by /u/me)" },
}).then((r) => r.json());

Implemented operations

POST /api/v1/access_token is unauthenticated (client-credentials). Every other route requires Authorization: Bearer <token> and a User-Agent header (missing UA → 429). State is in-memory and ephemeral.

POST /api/v1/access_token — issue an access token ({ access_token, token_type, expires_in, scope }).
GET /api/v1/me — the authenticated account (a t2 thing).
GET /r/:subreddit/hot.json — hot listing ({ kind: "Listing", data: { children: [{ kind: "t3", data }], after, before } }).
GET /r/:subreddit/about.json — subreddit info ({ kind: "t5", data }).
POST /api/submit — submit a post. Returns { json: { errors: [], data: { id, name, url } } }.

Service & inspection operations (parlel extensions)

GET / — service metadata.
GET /health — health check.
POST /__parlel/reset — reset all in-memory state.
GET /__parlel/posts — list captured posts.

Access via MCP / preview URL

When run inside a Daytona sandbox, this HTTP service is auto-exposed at the sandbox's preview URL. Send requests to the preview URL with the x-daytona-preview-token header to reach the service from outside the sandbox. The MCP layer surfaces the same endpoints described above.

Surface coverage

This emulator faithfully replicates the API surface most application code and agents exercise. Anything below the supported lines is either an intentional design choice for a fast, zero-cost local emulator (✓ By design) or a candidate for a future release (⟳ Roadmap) — never a silent inaccuracy.

Legend: ✅ fully supported · ◐ accepted (stored, not strictly enforced) · ✓ by design · ⟳ on the roadmap.

Feature	Status
OAuth token issuance	✅ Issues opaque tokens (not validated)
Identity (`/api/v1/me`)	✅ Supported
Hot listing / subreddit about	✅ Supported
Submit post	✅ Supported
`Listing` / `t2` / `t3` / `t5` thing shapes	✅ Supported
`User-Agent` requirement	✅ Enforced (missing → `429`)
Bearer token validity / scope enforcement	✓ By design — Any non-empty credential is accepted — no real secrets needed
Comments / voting / messaging	⟳ Roadmap
`new`/`top`/`rising` sorts, pagination cursors	◐ `hot` only; single page
Real posting to Reddit	✓ By design — Intentionally unsupported (fake only)

Configuration — `test.env`

Copy these into your test.env (used by the bridge sidecar flow). Tokens are Parlel's seeded test credentials — any non-empty value is accepted by the emulator, so you rarely need to change them. Swap in real credentials only when pointing at the live service in prod.env.

REDDIT_ACCESS_TOKEN=parlel
REDDIT_USER_AGENT=parlel/1.0 (by /u/parlel)
REDDIT_BASE_URL=http://parlel-bridge:4804