Custodian — record log

If someone edited this after the fact, you'd know.

Custodian is an append-only record log. Every entry is cryptographically linked to the one before it — so if anything is altered later, even by a system administrator, the break is provable, not just suspected.

Live proof

Try to tamper with it.

This is a real hash chain, computed in your browser. Edit any field below the way someone covering their tracks would — then watch what happens to every entry after it.

VERIFIED — 4 entries intact
Each row's hash is computed from its own fields plus the previous row's hash. Change one field, and every hash after it stops matching — there's no way to quietly fix just one entry.
Where this matters

Three situations where "trust me, I didn't change it" isn't good enough.

01

A record is disputed after an incident

A patient chart, an inspection report, a signed-off form — someone claims it was altered after the fact. Custodian proves whether it was, without relying on server logs someone could also edit.

02

Evidence changes hands

Every access, review, and modification of a document is chained in order. If a link in that chain is broken, you know exactly where and can't paper over it.

03

An auditor asks "how do you know?"

Instead of "we have logs," you show a chain that a third party can independently verify — including against an external timestamp you don't control.

How it works

No blockchain buzzwords. Just linked hashes.

1

Every action gets logged as an entry

Who did what, to which document, and a hash of that document's exact contents at that moment.

2

Each entry links to the last one

The entry's hash is computed from its own data plus the previous entry's hash — a chain, not a pile.

3

Anyone can verify the whole chain

Recompute the hashes and compare. If one doesn't match, you know precisely which entry was touched.

Want this for your records?

Early access is by conversation, not signup form — tell me what you're trying to prove and to whom.

Email me →