Bitcoin only · prices in sats
Cheapest L402 APIs for AI agents
132 L402 APIs answered HTTP 402 when probed. The cheapest costs 1 sat per call, 70 cost 10 sats or less and 103 cost 100 sats or less. The 25 cheapest are below.
live L402 APIs
132
each answered an unpaid HTTP 402 probe
cheapest per call
1 sat
$0.0008 at the snapshot rate
at or under 10 sats
70
of 132 · 103 are at or under 100 sats
| API | Provider | Category | Price per call | USD | Method | Probe |
|---|---|---|---|---|---|---|
| Loop Gateway | Loop XXI LLC | ai/inference | 1 sat | $0.0008 | POST | 402 seen 2026-10-23 |
| Raikiri: your first L402 purchase (1 sat test endpoint) | Raikiri | l402/tools | 1 sat | $0.0008 | GET | 402 seen 2026-10-23 |
| parsebit-lnd.fly.dev: Code explanation endpoint that accepts code or a code-file URL and r | parsebit-lnd.fly.dev | ai/code | 1 sat | $0.0008 | POST | 402 seen 2026-10-23 |
| parsebit-lnd.fly.dev: L402 | parsebit-lnd.fly.dev | ai/text | 1 sat | $0.0008 | POST | 402 seen 2026-10-23 |
| Air Quality Index: Current | Lightning Enable | data/environment | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| Convert HTML to Markdown or plain text (nothing fetched) (Tanod) | tanod | tools/web | 2 sat | $0.0016 | POST | 402 seen 2026-10-23 |
| Convert a color between hex, RGB, HSL and OKLCH and check WCAG contrast (Tanod) | tanod | media/images | 2 sat | $0.0016 | POST | 402 seen 2026-10-18 |
| Count word and n-gram frequencies in a text (Tanod) | tanod | ai/text | 2 sat | $0.0016 | POST | 402 seen 2026-10-18 |
| Crossref: DOI Lookup | Lightning Enable | data/science | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| DNS and WHOIS: Lookup | Lightning Enable | data/networking | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| Geocoding: Forward | Lightning Enable | data/location | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| IP Geolocation: Lookup | Lightning Enable | data/networking | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| Smart Wikipedia: Summary | Lightning Enable | data/reference | 2 sat | $0.0016 | GET | 402 seen 2026-10-18 |
| Census Query: Population | Lightning Enable | data/government | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| Compute perceptual hashes of an image, optionally compared (Tanod) | tanod | media/images | 3 sat | $0.0024 | POST | 402 seen 2026-10-18 |
| Detect a proxy contract, its kind and implementation address (Tanod) | tanod | crypto/onchain | 3 sat | $0.0024 | POST | 402 seen 2026-10-18 |
| Federal Register: Document Search | Lightning Enable | data/government | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| Nutrition Facts: Search | Lightning Enable | data/health | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| OpenAlex: Scholarly Data | Lightning Enable | data/science | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| Paper Scout: arXiv Search | Lightning Enable | data/science | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| Stock Quote: Real-Time | Lightning Enable | data/finance | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| Weather Intel: Forecast | Lightning Enable | data/weather | 3 sat | $0.0024 | GET | 402 seen 2026-10-18 |
| FRED: Economic Data | Lightning Enable | data/finance | 4 sat | $0.0033 | GET | 402 seen 2026-10-18 |
| Currency Exchange: Rates | Lightning Enable | data/finance | 5 sat | $0.0041 | GET | 402 seen 2026-10-18 |
| GitHub Repo Intel: Stats | Lightning Enable | data/developer | 5 sat | $0.0041 | GET | 402 seen 2026-10-18 |
Prices are the invoice amount decoded from the HTTP 402 challenge each endpoint returned to an unpaid request. Nothing was paid. The dollar figure uses $0.00081513 per sat (ratio of price_usd/price_sats in 402 Index API responses on 2026-10-15 (approximate, used only for sorting)).
All 132 L402 APIs → · Try a 21 test sat paywall → · Give an agent a Lightning budget with NWC →
How an agent pays one of these
- Pay the invoice. The 402 response carries a Lightning invoice. An NWC wallet or a Lightning node pays it. NWC for agents →
- Retry with the proof. L402 returns a macaroon with the invoice. The agent sends the macaroon and the payment preimage back to the API. No account and no card.
- Start free. The /try402 sandbox runs a real NUT-24 paywall with 21 test sats, so you can see the 402, payment and retry loop without real money.
Bitcoin for agents, the short answer → · Compare L402, x402, MPP and NUT-24 →
Plain-English meanings
- L402
- A way for an API to say “pay first”: it replies with a Lightning invoice, the agent pays a few sats, then gets its answer.
- Lightning
- Bitcoin’s fast, cheap payment layer: payments settle in seconds and can cost a fraction of a cent.
- HTTP 402
- “Payment Required”: a web status code a server sends when a request has to be paid for first.
- sats
- A satoshi (sat) is one hundred-millionth of a bitcoin.
- NWC
- Nostr Wallet Connect: lets an app or agent spend from your Lightning wallet within limits you set.
Data as of 2026-10-24. How we check: /method.