Cryptographic infrastructure for events worth proving.
Seal AI decisions, signed agreements, and any digital record to a tamper-evident chain — verifiable by anyone, modifiable by no one, including us. One MCP server. One API. One SDK. Built on Witnium's Digital Witness platform, in production years before AI compliance became a category — and ready for EU AI Act Article 12 from December 2027.
One protocol.
Every integration.
Choose the surface that fits your stack. The cryptographic guarantees are identical across all three. Move between them without rewriting your evidence trail.
MCP Server
Native Model Context Protocol server. Drop into any MCP-capable platform or agent framework.
- Zero-config for Claude Desktop, Cursor, any MCP host
- Same cryptographic proofs as the API and SDK
- Tool descriptions tuned for LLM tool-use
REST API
OpenAPI-described, language-agnostic, every framework. Witness an event with a single HTTP request.
- Idempotency keys on every write
- Webhooks on every state change
- SDKs auto-generated from OpenAPI
SDKs
Native libraries. TypeScript shipping today; Python, Go, Java in the pipeline.
- npm install @witnium-tech/witniumchain
- Five auth modes, one client
- Strongly typed end-to-end
Three lines from import to first witness.
No keys to generate in advance. No infrastructure to provision. The SDK handles PKCE login, refresh, signing, and witness allowance reservation. You handle your domain.
See the full quickstartimport { WitniumchainClient } from '@witnium-tech/witniumchain';
const wc = new WitniumchainClient({
baseUrl: 'https://auth.witniumchain.com',
chainBaseUrl: 'https://api.witniumchain.com',
accessToken: oauthToken,
});
// Open a witness intent against your contract
const intent = await wc.proposeWitnessV5(myContract, {
dataId: sha256(aiOutput),
context: { model: 'claude-sonnet-4.7', actor: userId },
requiredSigners: [myDelegatedKey],
});
// Once signatures collected, seal it on-chain
const sealed = await wc.finalizeWitnessV5(myContract, intent.intentId);
// → sealed.witnessId, verifiable foreverBuilt for what's coming
through 2028.
The Act phases in across four dates. Each one expands the market of organisations that need provable AI infrastructure. Witniumchain is the primitive built for all four.
Article 50 transparency obligations. GPAI provider obligations. Penalty regime begins.
Detectable watermarks on AI-generated content. Watermarks alone can be stripped — chains can't.
Article 12 enforcement. Tamper-evident logs across the lifetime of any high-risk AI system. Annex III enforceable.
Annex I obligations (medical devices, vehicles, regulated products).
We can't see what you witness.
Article 12 requires logs to be verifiable by a party independent of the AI vendor. Witniumchain takes the principle further: by design, Witnium cannot read your data, hold your keys, or alter your records.
Owner keypairs are generated in your browser using Ed25519. The private key never reaches our servers. Witness content is hashed client-side; what reaches Witnium is the SHA-256 fingerprint, never the underlying data. Signatures are produced locally and submitted as opaque bytes.
This isn't a privacy policy commitment. It's a structural property of the SDK and the protocol. If a regulator, a court, or a competitor asks Witnium to produce a customer's content, we can't — there is no version of us with that capability.
A log the vendor can modify is not evidence. A log the vendor cannot see, cannot touch, and cannot alter is. That difference is what makes a Witniumchain record audit-grade.
What we do see: operation metadata (timestamps, public keys, fingerprints, witness counts), required for credit accounting and chain integrity. What we cannot see: any content, any private key, any signing material. The chain is verifiable independently of us at witniumchain.com.
The same chain solves five other problems
your team already has.
Forensic readiness
Reconstruct what an AI decision was based on, after the fact. Court-grade, third-party-verifiable.
Internal governance
Board-level visibility into what your autonomous agents actually did.
Customer trust
Every output ships with a verifiable evidence chain. A differentiator that scales.
Multi-party workflows
Co-signed witnesses, attestation chains, evidence binders for any process where more than one party needs to agree.
Incident reconstruction
When something goes wrong, the chain tells you exactly which output, when, on which inputs, under which model version.
Built for the teams
regulators actually visit.
Legal AI platforms
For platforms serving EU law firms and in-house counsel. Article 12 is squarely in scope. Every output ships with a verifiable evidence chain. Customers gain regulatory readiness; you gain a defensible moat.
Enterprise AI agents
For platforms running autonomous agents on customer data. When an agent makes a decision that materially affects an employee, candidate, or customer, the chain proves what the agent saw, what it did, and why.
High-stakes vertical AI
For healthcare, financial services, public sector, and any AI domain where reconstruction matters. Witniumchain is the audit primitive that makes your AI defensible — in front of a regulator, an auditor, or a court.
We didn't build this for the AI Act.
The AI Act caught up to what we built.
Witnium Technologies was founded in Stockholm in 2016. We've been building Digital Witness — the cryptographic primitive that powers Witniumchain — for nearly a decade, in production with European law firms handling real legal evidence.
When the EU AI Act was drafted, our technology was already running. We didn't pivot to compliance. Compliance pivoted to us.
We are a Swedish company, in the EU jurisdiction the Act actually applies to. Our chain runs on infrastructure we control. Our cryptographic guarantees are not theoretical.
Get your credentials.
Run your first witness today.
Free tier includes 2,000 witnesses per month. No credit card required.