Crypto Sentiment API (x402)

Pay-per-call crypto sentiment API for AI agents. No API keys, no subscriptions — agents discover it, get an HTTP 402, pay in USDC on Base, and get the data.

Sentiment sources (all free, no keys required):

• Crypto news RSS (10 outlets) — CoinDesk, Cointelegraph, Decrypt, Bitcoin Magazine, The Block, CryptoSlate, NewsBTC, CryptoPotato, The Defiant, DL News
• Fear & Greed Index — alternative.me

Scoring: VADER sentiment analysis, extended with a crypto slang lexicon (moon, rekt, rug, hodl, bullish/bearish, etc.) so slang isn't scored as neutral.

---

1. Get a Base wallet address

You need an address to receive USDC payments. Any standard Ethereum-style wallet works on Base (e.g. Coinbase Wallet, MetaMask configured for Base). You do not need to give this app your private key — only the public address, to receive funds.

2. Run it locally (testnet — free, no real money)

cd crypto-sentiment-x402
cp .env.example .env
# edit .env and set PAY_TO_ADDRESS to your wallet address
pip install -r requirements.txt
uvicorn app.main:app --reload

Visit http://localhost:8000 — you'll see the API description. Calling http://localhost:8000/sentiment/BTC without payment returns an HTTP 402 with payment instructions, exactly what an agent's x402 client would see and act on automatically.

To actually test a paid call, use the official x402 test client (needs Base Sepolia testnet USDC — free from the Base Sepolia faucet):

pip install x402
python -m x402.examples.client --url http://localhost:8000/sentiment/BTC

3. Deploy (simplest path: Render.com)

1. Push this folder to a new GitHub repo.
2. Go to render.com → New → Blueprint → connect the repo. Render will read render.yaml automatically.
3. When prompted, set the PAY_TO_ADDRESS environment variable to your wallet address.
4. Deploy. Render builds the Dockerfile and gives you a public HTTPS URL like https://crypto-sentiment-x402.onrender.com.

That's it — testnet mode is on by default, so nothing costs real money until you flip X402_NETWORK to mainnet (step 4 below).

4. Go live with real USDC payments

1. Sign up for a free Coinbase Developer Platform account and create an API key — this is required for the mainnet facilitator (production-grade payment verification/settlement).
2. In Render, set:
   • X402_NETWORK=mainnet
   • CDP_API_KEY_ID=...
   • CDP_API_KEY_SECRET=...
   • PAY_TO_ADDRESS = your mainnet Base address (double-check it's not a testnet-only address)
3. Redeploy. Calls now settle real USDC on Base mainnet.

Start with a low price (X402_PRICE_USD, default $0.01) while you validate everything works end-to-end.

5. List it so AI agents can find and pay you

This is the x402 Bazaar — Coinbase's discovery layer, essentially a search engine for agents looking for x402 services.

• If you're using the CDP facilitator (i.e. you're on mainnet per step 4), your service becomes automatically discoverable in the Bazaar once you process your first real payment through it — no separate signup.
• To improve how well agents can find and understand it, keep the description field in app/main.py's RouteConfig clear and specific (already set) — that text is what shows up in Bazaar search results.
• You can browse the current Bazaar listing yourself at https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources (public, no key needed) to confirm your service appears after going live.
• Optional extra distribution: submit your API to x402bazaar.org, a community-run directory of x402 services, separate from Coinbase's own Bazaar.

MCP server (Claude Desktop / Claude Code)

Prefer agents calling this over MCP instead of raw HTTP? mcp_server.py wraps the same API as an MCP tool (crypto_sentiment) -- the server pays for each call from its own CDP-managed wallet, so callers never touch crypto directly. See MCP.md for setup.

Subscription tiers (Stripe, no crypto required)

Prefer a monthly bill over pay-per-call USDC? GET /v1/sentiment/{symbol} takes an X-API-Key header instead of an x402 payment, backed by Free / Starter ($15/mo) / Pro ($59/mo) tiers. See BILLING.md for setup, or GET /billing/pricing on a running instance for current pricing.

Sentiment-shift alerts

Watch a symbol and get pinged (webhook / Discord / Telegram) when its sentiment moves, instead of polling /sentiment yourself. Bundled into the Starter/Pro subscription tiers -- see ALERTS.md.

Historical dataset export

Sells access to the history of sentiment readings, not just the current one -- a background job takes one snapshot per symbol per day, and subscribers on the "Data Access" tier can export everything collected so far as CSV or JSON via GET /dataset/export. See DATASET.md (there's no backfilled history -- it only has data from whenever you turn the snapshot loop on).

Also on RapidAPI

Listed on the RapidAPI Hub for developers who'd rather discover and pay for it through RapidAPI's marketplace instead of Stripe or x402 directly. Same underlying data, served from GET /rapidapi/sentiment/{symbol} -- traffic is only accepted when it's routed through RapidAPI's proxy (validated via a shared secret header), so this endpoint isn't meant to be called directly. Plans there mirror the Stripe tiers: Free (100 req/mo), $15/mo (3,000 req), $59/mo (15,000 req).

Zapier & TradingView integrations

Route sentiment-shift alerts into Zapier (via the existing webhook channel -- no new endpoint needed) or enrich TradingView price alerts with live sentiment before relaying them to your webhook/Discord/ Telegram. See INTEGRATIONS.md.

API reference

Example paid response:

{
  "symbol": "BTC",
  "name": "Bitcoin",
  "overall_sentiment": {
    "sample_size": 42,
    "average_compound": 0.21,
    "label": "bullish",
    "positive_pct": 55.0,
    "negative_pct": 15.0,
    "neutral_pct": 30.0
  },
  "breakdown": {
    "news": { "...": "..." },
    "fear_greed_index": { "value": 62, "classification": "Greed" }
  },
  "sources": ["coindesk.com RSS", "..."]
}

Notes and limitations

• Reddit was removed as a source: Reddit's Responsible Builder Policy prohibits commercial use of their data without written approval, which this paid API would violate. app/sources/reddit.py is left in the repo unused in case that changes in the future.
• Coin coverage: app/coins.py has a starter list of ~15 symbols. Add more as needed — unmapped symbols still work, just with slightly less accurate news matching (falls back to matching on the symbol itself).
• Only supports the exact payment scheme on Base/EVM. The x402 SDK also supports Solana (ExactSvmServerScheme) if you want to accept SOL-based USDC too — see the commented-out import in app/main.py's dependencies.
• Add more paid endpoints (e.g. historical sentiment, multi-symbol batch queries) by adding entries to the routes dict in app/main.py.