# Bitcoin Timestamp via OpenTimestamps

> Bitcoin Timestamp via OpenTimestamps is a paid API for AI agents from agentsvc.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-16).

Timestamps text, a SHA-256 hash, or a URL's content on the Bitcoin blockchain using OpenTimestamps, returning a base64-encoded .ots proof file

## Facts

- Endpoint: POST https://agentsvc.io/api/v1/proxy/btc-timestamp?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bitcoin-timestamp-via-opentimestamps-b1386f31
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Fp6z2Fwg9MGESMIzfDhDD

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bitcoin-timestamp-via-opentimestamps-b1386f31 -d '<json body>'
```

Example prompt: Timestamp this contract text on Bitcoin using OpenTimestamps so I have a cryptographic proof it existed right now: 'This agreement between Party A and Party B was signed on June 1, 2025.'

## When to prefer this

Choose this endpoint when you need a decentralized, cryptographically verifiable proof that data existed at a specific moment in time, anchored to Bitcoin's immutable ledger using the open OpenTimestamps standard. It is ideal when the verifier has no reason to trust your server but will trust the Bitcoin blockchain. Prefer this over private timestamping services when interoperability with the open-source ots tool or third-party auditors matters, or when you need the lowest-cost Bitcoin-anchored proof without running your own node.

## Known failure modes

- Missing input: none of text, hash, or url provided — returns 400 error
- Invalid SHA-256 hash format — returns validation error
- URL is unreachable or returns an error at timestamping time — URL bytes cannot be captured
- Calendar server temporarily unavailable — proof may be delayed or fail
- Proof is initially pending (not yet anchored in a block) — verification must be retried after a few hours

## How this service works

Timestamp anything on Bitcoin with OpenTimestamps: send text, a SHA-256 hash or a URL and get a standard .ots proof (base64). Only a salted hash leaves our server. The public calendars anchor it in a Bitcoin block within hours; then btc-timestamp-verify returns the block and the complete proof, which anyone can check with the open-source ots tool. For contracts, AI outputs, datasets, invoices and web evidence.

## Output

A base64-encoded OpenTimestamps (.ots) proof file that records a salted hash of the input anchored to a Bitcoin block. The proof is pending calendar confirmation for the first few hours, after which it can be verified (via the companion btc-timestamp-verify endpoint or the open-source ots tool) to retrieve the Bitcoin block number and full cryptographic proof chain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Timestamp the exact bytes this URL returns now"
  },
  "hash": {
   "type": "string",
   "description": "SHA-256 hex, alternative to text"
  },
  "text": {
   "type": "string",
   "description": "Content to timestamp (hashed with SHA-256)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "success": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bitcoin-timestamp-via-opentimestamps-b1386f31/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentsvc.io](https://www.zero.xyz/host/agentsvc.io/llms.txt)