Arcaeon · for agents
A record of what your AI did, kept on your own machine.
Arcaeon keeps a record of what your agent did and shows you if anything in it was changed after it was written. This page is for the people who run agents first, then for the agents themselves.
Where Arcaeon is today
The desktop app
For Windows. There is no Linux download of this release. It keeps the record on your machine and shows whether it still checks out. The download is free and open to everyone, on the home page. How it works.
The engine
The free arcaeon package the app is built on. Every record is chained, so an edit, a removal or a reordering inside it breaks the chain, and a check names the first line that broke.
The witness
A pin puts your record's fingerprint on a public record anyone can check. That is what shows a record was cut short or rewritten after the pin. There is one witness today, and we run it. What it promises in writing.
What it proves, and what it does not
It proves the record was not changed after it was written, and, with a pin, not cut short or rewritten since the last pin. It does not prove that anything in the record is true, who wrote a line, or that nothing was left out. Every part, the same way.
You hold it on your own machine; we keep counts and paid accounts, never your record's content.
For agents
Connect today
The MCP server listed today is the ledger server. It lets an agent write to a record and check it.
pip install "arcaeon[mcp]" arcaeon mcp
arcaeon mcp --tools lists its tools without starting anything. Client setup is on the download page, and the full wiring list is on the page for agents.
The MCP door, in an earlier release
arcaeon-seal-mcp is a local stdio server with eight tools (record_write, record_read, record_correct, record_verify, record_pin, record_export, record_packet, record_stamp) that keeps an agent's notes in a sealed store the person owns. It ships with the desktop app (in an earlier release). Every read checks the store first; on a red note the door says so and holds the text back. record_pin makes a local pin on a plain store; on a folder the desktop app keeps, it hands the pin to the running app. A client that has the folder can still read a flagged note off the disk; the door flags it and holds the text back, it cannot stop a client that goes around it. Wiring and tools are on the page for agents.
Read the verdict, not the rows
arcaeon verify answers VERIFIED, BROKEN, or COULD NOT LOOK. Treat COULD NOT LOOK as not checked, never as a pass, and act on the verdict rather than on your own reading of the rows.
What it costs an agent
Writing and checking a record on your own machine needs no key and costs nothing. Pins need a key: 10 a month per key free, no login. Membership is $9 a month or $99 a year: unlimited pins, up to 100 an hour (not on sale yet). Packs of 200 for $5 or 1,000 for $20 never expire and are used after the month's free pins. Pricing.
Check us, not this page
Check us yourself · Browser tools · Disputes · Old package names · Witness health check
Machine-readable
/llms.txt (map) · /llms-full.txt (the agent pages, one file) · /ai.md (this page as markdown) · /.well-known/offers.json (catalog)
Everything in the catalog
Every listing, with its status and what it does not prove
Arcaeon
One package, one command: arcaeon <verb>. A record of what an agent did that shows any edit, removal or reorder inside it, plus a witness pin that shows if it is cut short, and a way for anyone who doubts it to check. pip install arcaeon, Python 3.10 or newer, zero dependencies in the base install. The package is free.
Record: log, verify, receipt, once, proxy, pin, deal. Prove: reconcile, audit, vet, badge, seal, baseline, compact. Save: distill, dedup, meter. One line per verb: /get.
Doors. For your AI: arcaeon mcp, after pip install "arcaeon[mcp]". Hosted: stamp works without a key inside a free daily allowance; pin --remote, seal and credits need ARCAEON_KEY and reach witness.arcaeon.io only when you run them (prices on /pricing). In a browser: /tools. For a dispute: /dispute, the free local pack.
What it does not prove: truncation without a pin (cut the newest rows and what is left still checks out; a witness pin closes that, as of the last pin); that any row is true; who wrote a row. A MATCHED reconcile means two tapes agree, and two recorders run by one party can write two agreeing tapes of a lie. vet and badge report what their checks found in the bytes they read, not a review by a person.
Used the old package names? /migrate maps each one to its new import and command. Witness Practices Statement: what the hosted witness promises in writing.
Arcaeon Verified Snapshot
A signed, timestamped capture of what a web page said at a specific moment. Schema arcaeon-verified-snapshot/2 binds the URL, capture time, the SHA-256 of the raw fetched bytes, the HTTP status, and the final URL after redirects into one Ed25519-signed statement, so a 404 body or a redirected body cannot be presented as a verified 200 of the URL you asked for. Change one byte of the content and the hash no longer matches.
Runs as a hosted service (build 0.1.9), billed per event where it is hosted, not a flat subscription here. Ask hello@arcaeon.io for a run.
What it does not prove: that the signing key is ours (compare it against the published key list, fetched separately); that anyone else saw the same page; anything about legacy /1 records' status or final URL, which sit outside the signature.
Talk to us
hello@arcaeon.io, for people and agents alike.