Everything you see below was computed in your browser. No server call. Three decisions went in; three signed, fingerprinted, chained records came out. Change one character anywhere — the seal breaks in front of you.
Prefer prose? How DONNA works in thirty seconds · Score your firm (3 min)
No new tool, no new habit. A partner speaks a decision; DONNA captures it as a structured record. Here are the three decisions on the Acme v. Northgate settlement:
Open DEMO-2024-0612 — Acme v Northgate. Conflict check is clear. Issue the engagement letter.
Approve the settlement offer of GBP 250,000, full and final. Counsel’s opinion says the range is GBP 180k–310k and the client has mandated to settle below GBP 300k. Confidence: high.
Settlement approved. Signed agreement received. Authorise release of funds, notify the client, and close the matter.
Each record carries a fingerprint (a SHA-256 hash — change one character and the fingerprint is completely different) and a digital signature (made with a demo key published below so your browser can check it). Each also carries the fingerprint of the record before it — so records are locked in order.
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This demo uses a deliberately public key. We published it here so your browser can verify the signatures right now — and it just did. In production the key works the other way: your firm holds a private signing key that only your firm can use, while anyone you share the chain with can still verify it. We are not verifying any production secret on this page; only this published demo key.
Each record is run through SHA-256 — a one-way fingerprint function. Change one character anywhere and the fingerprint changes completely, unpredictably, irreversibly. You cannot work backwards from the fingerprint to find what was there before.
Each record also carries the fingerprint of the record before it — like pages in a logbook where each page number references the page before it. So the records are locked into one order: alter any record and its own fingerprint breaks and every record after it loses its link. Your browser just recomputed all three fingerprints and re-checked every link — no key required, nothing sent anywhere.
The digital signature (Ed25519, a standard algorithm used in TLS, SSH, and e-passports) adds a second layer: the record was made by whoever holds the matching private key. In the demo, that key is the one published above — so your browser can verify it. In production, only your firm holds the private key, so only your firm can have made the record.
What this proves, exactly: every record is timestamped, signed, and chained to the one before it — so any later edit is detectable by anyone, without trusting us. Whether such a record is treated as evidence is a question of law for your jurisdiction; DONNA makes the record tamper-evident, not the legal ruling.
Everything on this page runs entirely in your browser. There is no server call, no analytics, no beacon. Nothing you type or click here is sent anywhere. Open DevTools → Network and watch: the tab stays empty.
Names, matters, and figures are fictional — constructed scenarios that exercise DONNA’s primitives without exposing any real client material. The pattern is realistic; the data is invented.
The sample pack uses the same structure and the same real Ed25519 signature scheme demonstrated above (each record carries its own public key, so it verifies with no shared secret). The names, matters, and figures inside it are illustrative — the cryptographic structure is real, the client data is invented.