The Bitcoin + x402 resource hub
Build something useful.
Estimate a Bitcoin fee, add data to an app, or build a service an agent can pay to use. Start with the task you need to finish.
Selected and reviewed September 8, 2026. External services have their own availability and terms. Our templates are labeled below; no sponsored placements.
01 / Bitcoin
Understand your next transaction.
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Calculate the network fee
Compare priority tiers in sat/vB and estimated costs in sats. Enter the virtual size from your wallet; timing targets are estimates.
On BitcoinsAPI · free · no wallet connection
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Use the free Bitcoin fee API
A copyable request, a JavaScript example, and complete response schemas. Check source timestamps before using a cached response.
On BitcoinsAPI · free · no API key
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Explore the Bitcoin mempool
See blocks and pending transactions at mempool.space, the upstream source for our fee snapshot. Building your own integration? Read its API documentation.
External · mempool.space
02 / x402
Give an agent a way to pay.
x402 is an HTTP payment protocol. Bitcoin fee data is what this site provides; our optional paid API uses USDC on Base. It does not charge a Bitcoin network fee.
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Call a paid API
The official buyer guide covers SDK clients, supported networks, payment requirements, and settlement responses. Choose an explicit spending limit before signing requests.
Official documentation · buyer path
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Accept payment for an API
The official seller guide explains route pricing, payment middleware, and facilitator setup. Pair it with a framework starter below.
Official documentation · seller path
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Make a resource discoverable
Bazaar describes inputs, outputs, and pricing so agents can find and evaluate a service. A custom discovery file alone does not establish a Bazaar listing.
Official documentation · discovery extension
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Understand signed offers and receipts
Learn how the extension binds an offer and a receipt to a resource. Check SDK and facilitator support before assuming an extension is available.
Official documentation · optional extension
03 / Our open-source templates
Start with your framework.
Each template has a free route and a paid route using the official x402 SDK. Set your own recipient and an operating facilitator; our former hosted facilitator is paused.
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Express starter
A minimal Node.js server with x402 middleware. A small starting point for an existing API.
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FastAPI starter
A Python service using the official x402 middleware and EVM dependencies.
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Next.js starter
Payment-gated App Router endpoints using the official Next.js integration.
Templates updated September 7, 2026. Their fixture tests cover configuration, a free response, and an unpaid challenge. Those tests do not prove live settlement.
04 / In practice
What is worth building around?
Useful paid results are the starting point: search, research, and other capabilities an agent needs to finish a task. You.com documents machine payments for its search and research APIs, including x402 and MPP.
AWS made AgentCore Payments generally available in August 2026, with controls for agent transactions and support for x402 and MPP. Integration quality now includes spending controls, discovery, and handling failed requests.
Our focus is a useful Bitcoin tool and a clear integration path. You can inspect our timing method, payment evidence, and current availability.
PausedPayments are paused. No payment proof is processed. The free fee preview is available without a wallet.