Anchor a file's SHA-256 fingerprint to Bitcoin. The file never leaves the device.
Copy the AI prompt to install this server into Claude Code, Cursor, or another agent β or use 1-click editor setup below.
π‘ Paste into ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows)
Anchor any file to the Bitcoin blockchain in about ten seconds. For photographers, journalists, indie creators, and developers who need to prove a file existed before a given moment β especially before an AI model saw it. Files never leave the browser; only the 32-byte SHA-256 fingerprint is submitted. Free tier (3 anchors/24h), $19 Writer Pack (10 anchors), $9/mo Standing Order (unlimited), $19/mo Creator (capture-time app + API + verifier badge).
Four steps a developer can run from a terminal, no signup, no install
beyond curl and shasum.
Compute the SHA-256 of any file on disk:
Submit the hash to the public anchor endpoint:
The response is a JSON receipt with a receipt_id and a list of the
OpenTimestamps calendars that accepted the submission.
Pull the receipt back later by ID (or visit /r/<id>):
Verify offline against the original file with the standalone verifier (no orphograph code, MIT, ~100 lines of stdlib Python):
The verifier re-hashes the file (or walks the folder) locally and
confirms the result reproduces the manifest's root. Add --ots <path>.ots to also invoke the OpenTimestamps client and check the
chain witness references the same root.
Orphograph ships an MCP server: a single stdlib-only Python file (682
lines, MIT) that implements the Model Context Protocol β JSON-RPC 2.0 over
stdio, protocol version 2024-11-05, with the initialize, tools/list,
and tools/call methods implemented directly, no SDK β so AI agents and
MCP hosts (Claude Code, Claude Desktop, or any MCP client) can anchor and
verify files as tool calls.
Listed in the official MCP registry as io.github.Orphograph/orphograph.
MCP tools exposed (full JSON Schemas in mcp/manifest.json):
| Tool | What it does |
|---|---|
orphograph_anchor_file | Hash a local file (SHA-256/SHA-512 computed in-process) and anchor the fingerprints to Bitcoin via OpenTimestamps. The file body never leaves the machine. |
orphograph_anchor_folder | Build an RFC-6962 Merkle manifest over a folder and anchor one root that covers every file. |
orphograph_anchor_output | Anchor an AI agent's generated output at creation time β provenance receipts for agent actions. |
orphograph_verify_receipt | Look up what this office recorded for a receipt: anchored hashes, calendar attestation counts, and when the Bitcoin pin was observed. A lookup, not an independent chain check β run ots verify for that. No API key required. |
orphograph_verify_lineage | Walk an edit-lineage chain back through its committed parents and report the ordering the anchors establish. |
orphograph_list_vault | List the authenticated subscriber's anchored receipts. |
Quickstart (stdio transport):
The free tier needs no API key; set ORPHO_API_KEY to use vault features.
An MCPB bundle is attached to release mcp-v0.1.0, and
mcp/Dockerfile builds a minimal container for MCP
directory crawlers β the server starts and answers MCP introspection with
no configuration. Full tool schemas and options: mcp/README.md.
Python 3.11+ stdlib only on the server (http.server, urllib, hashlib,
json, secrets, fcntl) β zero pip dependencies in the anchor engine.
Vanilla HTML + CSS + JS on the client, hashing via WebCrypto
SubtleCrypto.digest so file bytes never leave the browser. Each anchor
fans out a single 32-byte POST to five independent OpenTimestamps
calendars (a.pool, b.pool, alice, finney, btc.catallaxy); the calendars
batch many users' hashes into a single Merkle root and write the root to
Bitcoin roughly hourly, which is why our marginal on-chain cost is
effectively zero. The .ots proofs are stored per-receipt and verify
against the public Bitcoin chain forever, with or without us. Bitcoin
custody is receive-only: a single watch-only address printed in
btc_address.txt accepts payments; no signing keys live on production
hosts.
By spring 2026 a large share of new images circulating online are AI-generated or AI-modified. Watermarks can be stripped, C2PA labels can be re-signed, EXIF is one shell command away from being anything you want. What survives that is cryptographic proof β a Bitcoin block that already existed at a known time, with the hash of your file committed inside it. Orphograph is the cheapest, most boring way to put a fingerprint of your work into that block before anyone disputes it. Long-form on the thesis: /blog/written-by-an-ai.
What touches what, in one table.
| Datum | Stays on your machine | Sent to server | Submitted to OTS calendars | Notes |
|---|---|---|---|---|
| File bytes | yes | never | never | WebCrypto hashes locally |
| SHA-256 (32 bytes) | yes | yes | yes | The only thing on-chain |
| SHA-512 sibling (64 bytes) | yes | yes | no | Quantum hedge; OPTIONAL (client-supplied), stored in receipt only, never anchored |
| Filename / label | yes | opt-in | no | Off by default; pass --label to include |
| Email address | yes | only when needed | no | Required only for Pack delivery + Personal subscriptions |
| IP address | n/a | truncated to /24 (IPv4) or /48 (IPv6) | no | Full IPs are never persisted |
Run the test suite at any time:
The smoke test hits live OTS calendars and requires network:
Single-container Fly.io with a mounted volume for receipts/ and the
JSONL ledgers; Stripe webhook verification, Resend for transactional
email, CSP default-src 'self'. Step-by-step in
deploy/FLY_PREFLIGHT.md.
| Tier | Price | What's included |
|---|---|---|
| Free | $0 | 3 anchors per 24 hours per IP-prefix |
| Writer Pack | $19 one-time | 10 anchors, claim code by email, never expires, skips rate limit |
| Standing Order | $9/mo or $60/yr | Unlimited anchors, email delivery, account dashboard, anchor history |
| Creator | $19/mo | Personal + Orphograph Capture (capture-time desktop app) + API access + verifier badge |
The $19 / $9 price points are set deliberately low.
The wedge is browser-based UX plus the open-source verifier β not the
cryptography, which is the public OpenTimestamps protocol.
dist/orphograph-verify/ β MIT. Vendor it, ship it, audit it. This
is the trust artifact: a receipt produced today must verify against
Bitcoin five years from now even if orphograph.com no longer exists.marketplace/orphograph-plugin/ β MIT.The privacy contract of Orphograph is structural, not promissory. Files are hashed in the user's browser; only the SHA-256 (and SHA-512) fingerprint is transmitted. The server cannot reconstruct, identify, or retransmit the file, because it never receives the file. This property holds independently of who maintains the code.
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