Dynamic Feed Starter

Build a live-data agent that can prove its data is real — in one serverless function, with zero npm dependencies.

This is the smallest possible app on Dynamic Feed: a static page + one function that pulls keyless live data (earthquakes, US Treasury yields, exploited CVEs, hazards near any point) and then verifies an Ed25519 signature in your browser — so you can watch a green ✓ signature VALID — verified in your browser badge light up on data that was measured seconds ago.

One click. No API key. No environment variables.

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What it demonstrates

1. Keyless live data — api/feed.js makes a single POST https://dynamicfeed.ai/v1/batch call that fans out to three tools server-side (earthquakes, treasury_yields, exploited_vulnerabilities), plus an optional GET /v1/nearby?lat&lon signed hazard scan around any point. No key, no signup, no SDK.
2. In-browser signature verification — the page fetches a fresh signed attestation from GET https://dynamicfeed.ai/v1/attest, strips the signature block, re-canonicalizes the envelope byte-for-byte (json-sorted-compact — see the standard), and verifies the detached Ed25519 signature against the published key at /.well-known/keys using @noble/ed25519. Verification happens in your browser — you are not trusting this app, or even Dynamic Feed's web server, to tell you the data is genuine.
3. Tamper evidence — hit the “run tamper test” button: it flips a single digit of the data and re-verifies. The signature fails instantly. That is the whole point — signed data cannot be quietly altered between source and agent.

Run locally

Zero-install (Node ≥ 18, nothing to npm install):

node dev-server.js
# → http://localhost:3000

Or with Vercel's emulator:

npx vercel dev

Try the function directly:

curl http://localhost:3000/api/feed | python3 -m json.tool
curl "http://localhost:3000/api/feed?lat=-33.87&lon=151.21"   # + signed hazards near Sydney

Files

File	Purpose
api/feed.js	the entire backend — one Vercel serverless function, global fetch, no deps
index.html	the dashboard + in-browser verification UI
verify.js	Ed25519 verifier (adapted from the official dynamicfeed.ai/verify.js for cross-origin use)
canon.js	the json-sorted-compact canonicalization — lossless number-preserving parse, Python-ensure_ascii escaping
style.css	dark, minimal, mono
dev-server.js	optional zero-install local server (node dev-server.js)

Why canonicalization is fussy (and why that's in canon.js)

A naive JSON.parse → JSON.stringify round-trip silently changes bytes — float representation (151.21 can become 151.20999999999998) and non-ASCII escaping (the signer escapes the arrow character → to the six ASCII bytes \u2192) — and a single changed byte breaks an Ed25519 signature. canon.js parses losslessly (numbers kept verbatim as wire text) and re-serializes exactly the way the signer does. The full recipe is published at dynamicfeed.ai/standard.

Make it yours

• Swap the tools in api/feed.js — there are 50+ keyless tools (weather, flights, satellites, sanctions, shipping, AI-model pricing, …). The full self-describing catalog: dynamicfeed.ai/llms-full.txt
• Point the nearby-hazards card at your own coordinates
• Need higher rate limits or key-gated REST? dynamicfeed.ai

Links

• dynamicfeed.ai — the live-data layer for AI agents
• /standard — the signed-envelope + canonicalization spec
• /proof — verify a live envelope yourself, right now
• /llms-full.txt — every tool, self-describing, agent-readable

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MIT — fork it, ship it.