Cryptographically verifiable audit logs

Provable audit integrity for critical application events

You already record critical actions. Untamper makes them defensible — with tamper-evident chains your team and auditors can independently verify.

No credit card required · Free tier includes 10k events/month

You already record critical actions. Untamper makes them defensible. Cryptographic chain verification · Independent auditor access · SDK in minutes

Why Untamper

Audit logs that hold up under scrutiny

Not just logged — provable

Every event is hashed and chained to the previous one. Altering any record breaks the chain — a fact anyone with the public key can verify, independently, any time.

Built for high-risk events

Purpose-built for the 1% of events that matter: admin actions, privilege changes, sensitive data access. Not a general-purpose logging firehose.

Auditor-ready exports

One-click exports with cryptographic verification proofs attached. Your auditors can verify integrity without touching your infrastructure.

How it works

From event to verifiable proof in minutes

Four steps — two are automatic.

01

Send events

Instrument your app with our SDK. One function call per critical event — actor, action, target, metadata.

untamper.log({
  actor: { id: user.id, type: 'admin' },
  action: 'role.grant',
  target: { id: org.id }
})
02

Normalize & secure

Events are canonicalized, timestamped with a trusted source, and persisted with structured metadata.

03

Tamper-evident via crypto

Each event is SHA-256 hashed against its predecessor, forming a cryptographic chain. Any alteration invalidates all subsequent hashes.

04

Verify later

Run verification any time — from our dashboard, the CLI, or your own tooling using the public verification API.

const result = await untamper.verification.verifyLogs(logs)
console.log(result.valid, result.totalLogs)

Compare

Why not just use what you already have?

Most tools record events. None of them make those events provably unaltered.

FeatureUntamperDatadogNative LogsGeneric Stack
Critical event focus
Independent chain verification
Export with verification proof
Typed SDK with structured events
Full-text + metadata search
Auditor access without infra access
Tamper detection

Yes   Partial   No

Trust model

How Untamper makes records provable

We don't ask you to trust that logs weren't altered. We give you the math to verify it yourself.

Read the full security model →

What gets hashed

The canonical event payload: actor, action, target, timestamp, metadata — plus the hash of the previous event in the chain.

Chain model

Each event's hash depends on the previous. Insert, modify, or delete any event and all subsequent hashes become invalid — automatically detectable.

How to verify

Anyone with the public API can recompute the chain. Our CLI, SDK, and dashboard all expose one-command verification.

Start building free

Instrument your first critical event in minutes. Free tier includes 10,000 events per month with full chain verification.