Glossary

Terms you'll encounter when building with Hypercerts, ordered by how soon you'll need them.

Hypercert

A structured digital record of a contribution: who did what, when, where, and with what evidence. The core primitive of the protocol. Technically, a hypercert is an activity claim record with linked contributions, evidence, measurements, and evaluations.

Activity claim

The central record in the hypercerts data model. Describes the work that was done, when, and in what scope. Created using repo.hypercerts.create() in the SDK. Lexicon: org.hypercerts.claim.activity.

AT-URI

The permanent, globally unique identifier for a record. Looks like at://did:plc:abc123/org.hypercerts.claim.activity/3k7. You'll see these in every API response — they're how records reference each other.

DID (Decentralized Identifier)

A permanent identifier for a user or organization. Looks like did:plc:abc123xyz. You get one when you create an account on certified.app or Bluesky. Your DID never changes, even if you switch servers or handles. Every record you create carries your DID as the author.

CID (Content Identifier)

A cryptographic hash of a record's content. When you reference another record, you include both its AT-URI and CID — this makes the reference tamper-evident. If the record changes, the CID changes, and the mismatch is detectable.

Strong reference

A reference to another record that includes both the AT-URI and CID. Used when one record points to another (e.g., an evaluation referencing an activity claim). The CID ensures you're referencing a specific version of the record.

Evaluation

A third-party assessment of a hypercert. Created on the evaluator's own account, not the original author's. Lexicon: org.hypercerts.claim.evaluation.

Evidence

Supporting documentation attached to a hypercert — a URL, uploaded file, or IPFS link. Lexicon: org.hypercerts.claim.evidence.

Measurement

A quantitative observation attached to a hypercert (e.g., "12 pages written", "50 tons CO₂ reduced"). Lexicon: org.hypercerts.claim.measurement.

Contribution

A record describing a specific contributor's role in an activity claim, including their DID, role description, and date range. Lexicon: org.hypercerts.claim.contribution.

Collection

A group of hypercerts with a shared property, where each claim has a weight. Used for projects or portfolios. Lexicon: org.hypercerts.claim.collection.

Lexicon

A versioned schema that defines the structure of a record type. For example, org.hypercerts.claim.activity defines the required and optional fields for an activity claim. Lexicons enable interoperability — any app that knows the schema can read the record. See Introduction to Lexicons.

Work scope

The "what" dimension of a hypercert, defined using logical operators (allOf, anyOf, noneOf) to precisely bound the work being claimed. See Defining Work Scopes for details.

Hypergoat / Hyperindex

The AppView server that indexes hypercert records across the network and exposes them via a GraphQL API at hypergoat.certified.app/graphql. This is how applications query hypercert data without reading from individual servers directly.

PDS (Personal Data Server)

The server where your records are stored. You interact with it through the SDK — you don't need to manage it directly. You can use the Hypercerts Foundation's PDS, Bluesky's, or self-host one. Records are portable between PDS instances.

Certified

The ATProto identity provider for the Hypercerts ecosystem. When you sign up at certified.app, you get a DID, a PDS, and an embedded wallet. See Account & Identity Setup.