{"@context":"https://schema.org","@type":"Dataset","name":"Source router: primary sources for bitcoin and digital-asset facts","description":"For each class of question an agent asks about bitcoin custody and market structure, the primary or near-primary source to read, with cadence, access terms and whether the URL answered today. Proof of Custody's own datasets appear where it is the primary publisher.","url":"https://proofofcustody.io/data/sources.json","creator":{"@type":"Organization","name":"Proof of Custody","url":"https://proofofcustody.io"},"publisher":{"@type":"Organization","name":"Proof of Custody","url":"https://proofofcustody.io"},"license":"https://creativecommons.org/licenses/by/4.0/","isAccessibleForFree":true,"inLanguage":"en","dateModified":"2026-10-20T03:10:16.132Z","asOf":"2026-10-20T03:10:16.132Z","status":"fresh","cadence":"Registry edited by hand; reachability checked daily","upstream":null,"method":"Every URL is fetched once a day. `reachable` is false when it did not answer with a 2xx or 3xx status; the MCP find_source tool only returns reachable entries.","citation":"Proof of Custody, \"Source router: primary sources for bitcoin and digital-asset facts\", https://proofofcustody.io/data/sources.json, as of 2026-10-20","publisherDisclosure":"Proof of Custody is published by Onramp Bitcoin, which is scored by the same methodology as every other platform and does not control rankings or coverage.","readMe":{"staleness":"Check `status` and `asOf`. A `stale` status means the last pull failed and this is the previous snapshot. The change feed at /data/changes.json lists corrections and methodology changes.","coverage":"Coverage is selected, not exhaustive. Absence from a dataset is not evidence about the thing absent.","upstream":"Where `upstream` names another publisher, the numbers are theirs, credited; Proof of Custody adds the envelope, the as-of discipline and the daily check.","howToUse":"Filter by `topic` or search `tags`. Prefer `primary: true` entries for a fact you intend to cite; the others are aggregators that credit their own sources."},"topics":["agent-indexes","agentic-commerce","corporate-treasuries","custody-incidents","custody-scores","etf-custody","etf-holdings","filings","hardware-advisories","hardware-wallets","mcp","network","proof-of-reserves","regulators","stablecoin-attestations","stablecoin-supply","staleness","tokenized-assets","x402"],"count":34,"reachable":28,"sources":[{"id":"poc-scores","topic":"custody-scores","tags":["custody","exchange","ira","etf","scores","comparison"],"name":"Proof of Custody platform scores","publisher":"Proof of Custody","url":"https://proofofcustody.io/data/bitcoin-custody-dataset.json","what":"91 bitcoin custody, exchange, IRA, ETF and lender platforms scored on one published methodology, with custody model and single point of failure.","cadence":"Monthly, first Monday","access":"Open, CC BY 4.0, no key","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"poc-incidents","topic":"custody-incidents","tags":["incident","hack","failure","insolvency","coldcard","registry"],"name":"Proof of Custody custody failure registry","publisher":"Proof of Custody","url":"https://proofofcustody.io/data/custody-incidents.json","what":"Dated custody failures since 2011 with the configurations each failure class could reach, reported loss and named source, plus live incident records.","cadence":"When verified against a primary source","access":"Open, CC BY 4.0","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"poc-hardware","topic":"hardware-wallets","tags":["hardware","coldcard","trezor","ledger","foundation","firmware","entropy"],"name":"Proof of Custody hardware wallet rubric","publisher":"Proof of Custody","url":"https://proofofcustody.io/data/hardware-wallet-scores.json","what":"Devices scored on entropy, firmware, supply chain, disclosure conduct, interoperability and privacy, with the reason for every score.","cadence":"On disclosure events","access":"Open, CC BY 4.0","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"poc-changes","topic":"staleness","tags":["corrections","changelog","stale","cache"],"name":"Proof of Custody change feed","publisher":"Proof of Custody","url":"https://proofofcustody.io/data/changes.json","what":"Every correction and methodology change with a stable id and the pages it affects.","cadence":"As published","access":"Open, CC BY 4.0","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"poc-etf-custody","topic":"etf-custody","tags":["etf","ibit","fbtc","gbtc","custodian","coinbase","concentration"],"name":"Proof of Custody ETF custody concentration","publisher":"Proof of Custody","url":"https://proofofcustody.io/data/etf-custody-concentration.json","what":"Which custodian holds each US spot bitcoin ETF's bitcoin, derived from SEC filings, with the Nakamoto coefficient at the custody layer.","cadence":"On filings; net-asset freshness checked daily","access":"Open, CC BY 4.0","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"sec-edgar-fts","topic":"filings","tags":["sec","edgar","filing","10-k","s-1","custodian agreement","etf"],"name":"SEC EDGAR full-text search","publisher":"US Securities and Exchange Commission","url":"https://efts.sec.gov/LATEST/search-index?q=%22bitcoin%20custodian%22","what":"Full-text search across filings since 2001. The custodian for every US spot bitcoin ETF is named in its prospectus and annual report.","cadence":"Continuous","access":"Open, public domain","primary":true,"howToQuery":"Search the fund name plus \"custodian\"; read the latest 10-K or S-1.","reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"ishares-ibit","topic":"etf-holdings","tags":["etf","ibit","blackrock","holdings","net assets"],"name":"iShares Bitcoin Trust ETF (IBIT) fund page","publisher":"BlackRock","url":"https://www.ishares.com/us/products/333011/ishares-bitcoin-trust-etf","what":"Net assets, NAV, shares outstanding and the daily holdings file for the largest spot bitcoin ETF.","cadence":"Daily","access":"Open","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"grayscale-gbtc","topic":"etf-holdings","tags":["etf","gbtc","grayscale","holdings"],"name":"Grayscale Bitcoin Trust ETF (GBTC) fund page","publisher":"Grayscale","url":"https://etfs.grayscale.com/gbtc","what":"Bitcoin per share, net assets and holdings for GBTC.","cadence":"Daily","access":"Open","primary":true,"reachable":false,"httpStatus":429,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"bitwise-bitb","topic":"etf-holdings","tags":["etf","bitb","bitwise","holdings","on-chain","addresses"],"name":"Bitwise Bitcoin ETF (BITB)","publisher":"Bitwise","url":"https://bitbetf.com/","what":"Holdings and the published on-chain addresses for the trust's bitcoin.","cadence":"Daily","access":"Open","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"ark-arkb","topic":"etf-holdings","tags":["etf","arkb","ark","21shares","holdings"],"name":"ARK 21Shares Bitcoin ETF (ARKB)","publisher":"ARK Invest / 21Shares","url":"https://www.ark-funds.com/funds/arkb/","what":"Holdings and net assets for ARKB.","cadence":"Daily","access":"Open","primary":true,"reachable":false,"httpStatus":403,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"defillama-stablecoins","topic":"stablecoin-supply","tags":["stablecoin","usdt","usdc","supply","circulating","chains"],"name":"DefiLlama stablecoins API","publisher":"DefiLlama","url":"https://stablecoins.llama.fi/stablecoins?includePrices=false","what":"Circulating supply of every tracked stablecoin by peg type and chain. The source behind Proof of Custody's daily stablecoin snapshot.","cadence":"Continuous","access":"Open API, no key; attribute DefiLlama","primary":false,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"tether-transparency","topic":"stablecoin-attestations","tags":["stablecoin","usdt","tether","reserves","attestation"],"name":"Tether transparency and attestations","publisher":"Tether","url":"https://tether.to/en/transparency/","what":"Issuer-published reserves breakdown and quarterly attestations for USDT.","cadence":"Daily totals, quarterly attestations","access":"Open","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"circle-transparency","topic":"stablecoin-attestations","tags":["stablecoin","usdc","circle","reserves","attestation"],"name":"Circle USDC transparency","publisher":"Circle","url":"https://www.circle.com/transparency","what":"Issuer-published reserve composition and monthly attestations for USDC.","cadence":"Monthly attestations","access":"Open","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"rwa-xyz","topic":"tokenized-assets","tags":["rwa","tokenized","treasuries","tokenization","stablecoin","private credit","buidl","usyc"],"name":"RWA.xyz","publisher":"RWA.xyz","url":"https://app.rwa.xyz/","what":"Tokenized real-world assets by asset class (US Treasury funds, non-US government debt, credit, stocks, commodities, real estate), network, platform and issuer, plus stablecoins. The reference dataset for tokenization; the API and most metrics require a login or an enterprise key, so Proof of Custody points here rather than redistributing.","cadence":"Daily","access":"Site free with login for most metrics; enterprise API; All Rights Reserved","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"rwa-xyz-docs","topic":"tokenized-assets","tags":["rwa","tokenized","methodology","api","mcp"],"name":"RWA.xyz documentation and MCP server","publisher":"RWA.xyz","url":"https://docs.rwa.xyz/","what":"Methodology, data model and API reference, and an MCP server for connecting RWA.xyz data to an assistant.","cadence":"As published","access":"Docs open; API key required","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"defillama-rwa","topic":"tokenized-assets","tags":["rwa","tokenized","tvl","protocols"],"name":"DefiLlama protocols (RWA category)","publisher":"DefiLlama","url":"https://defillama.com/protocols/RWA","what":"TVL by protocol in the RWA category. 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The source behind Proof of Custody's daily x402 services snapshot.","cadence":"Continuous","access":"Open, no key","primary":true,"howToQuery":"Paginate with limit and offset; the total is in pagination.total.","reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"x402-docs","topic":"x402","tags":["x402","docs","facilitator","coinbase"],"name":"Coinbase x402 documentation","publisher":"Coinbase Developer Platform","url":"https://docs.cdp.coinbase.com/x402/welcome","what":"How to accept and make x402 payments, facilitators, supported networks.","cadence":"As published","access":"Open","primary":true,"reachable":true,"httpStatus":200,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"ap2","topic":"agentic-commerce","tags":["ap2","agent payments protocol","google","mandates","agentic commerce"],"name":"Agent Payments Protocol (AP2)","publisher":"Google and partners","url":"https://ap2-protocol.org/","what":"Open protocol for agent-initiated payments with verifiable mandates.","cadence":"As published","access":"Open","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"openai-commerce","topic":"agentic-commerce","tags":["acp","agentic commerce protocol","openai","stripe","instant checkout","chatgpt"],"name":"OpenAI commerce developer docs (Agentic Commerce Protocol)","publisher":"OpenAI","url":"https://developers.openai.com/commerce","what":"How merchants expose products and checkout to ChatGPT through the Agentic Commerce Protocol.","cadence":"As published","access":"Open","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"ucp","topic":"agentic-commerce","tags":["ucp","universal commerce protocol","google","shopify","agentic shopping"],"name":"Universal Commerce Protocol","publisher":"Google, Shopify and partners","url":"https://ucp.dev/","what":"Open standard for agents to discover, cart and buy from participating merchants through one published capability profile.","cadence":"As published","access":"Open","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"},{"id":"mcp-registry","topic":"mcp","tags":["mcp","registry","servers","agents","tools"],"name":"Official MCP registry","publisher":"Model Context Protocol project","url":"https://registry.modelcontextprotocol.io/v0/servers?search=bitcoin&limit=20","what":"The open registry of MCP servers. 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Proof of Custody does not republish network data; go here.","cadence":"Live","access":"Open, public API","primary":true,"reachable":true,"httpStatus":206,"lastChecked":"2026-10-20T03:10:16.132Z"}]}