Every verification we record, every correction we make, and every claim we refuse to make is appended to a hash chain that cannot be edited without breaking. Your browser is checking the whole thing right now — with our server having no say in the result.
Pick any record we have published, change it, and watch this page catch you. The check that runs is the same one that ran a moment ago on the real chain; the only difference is that you are the one doing the tampering. Nothing you do here leaves your browser.
Why this matters: a hash chain only proves anything if the reader can recompute it without our help. Every clinic verification, every correction and every claim we withhold is an entry in this chain — so if we ever quietly revised one, this page would say so on our own website.
A clinic, a claim we make, a file we changed. If it isn't here, we didn't record it — and that is itself an answer.
A ledger that only holds good news is marketing. This one records our corrections, the claims we withhold because we can't stand behind them, and the size of our own verification backlog.
Each entry's hash covers its own contents and the hash before it. Change one character anywhere and every subsequent hash changes, so the chain stops matching its published head. Remove an entry and the sequence gaps. There is nowhere to hide an edit.
Download /fixtures/ledger.json and run this — no JetPatient
code involved:
node -e '
const c=require("crypto"),d=require("./ledger.json");
const K=v=>v===null||typeof v!=="object"?JSON.stringify(v)
:Array.isArray(v)?"["+v.map(K).join(",")+"]"
:"{"+Object.keys(v).sort().map(k=>JSON.stringify(k)+":"+K(v[k])).join(",")+"}";
let p="0".repeat(64),bad=0;
for(const[i,e]of d.entries.entries()){
const h=c.createHash("sha256").update(K({seq:e.seq,ts:e.ts,kind:e.kind,
subject:e.subject,payload:e.payload,prev:e.prev})).digest("hex");
if(e.seq!==i||e.prev!==p||e.hash!==h)bad++;p=e.hash;}
console.log(bad?"BROKEN":"intact",d.entries.length,"entries; head",p);'
If that prints anything other than intact and a head matching the one above,
we have altered the record and you should tell us — and everyone else.