Implementations

Independent tools that implement one or more JPS conformance classes or test the specification's semantics. A listing here is not certification, endorsement, or authority over the specification.

The specification is the authority. No implementation — including the reference runtime — is normative. A claim belongs to its claimant, one conformance class, and one exact specVersion. Corpus results are required but non-exhaustive evidence; they are not certification. Any implementation that satisfies the complete requirements of the same class for the same exact version is equally valid. No conformance class establishes factual grounding, authorization, safety, or operational fitness.

Available implementations

Open source · Apache-2.0 · maintained with the specification

judgment-pack

The project's vendor-neutral reference runtime; the command it installs is jpack. It validates the carrier, structural schema, and semantic references of a JPS document against an immutable specification release. Its evaluator produces a disposition from supplied inputs, and the runtime states an evaluator-conformance claim in full in its own repository. Evaluating surfaces stay labelled experimental, which reports their stability, never their conformance. A disposition never establishes truth, authorization, safety, or fitness, does not authorize an action, and the runtime fetches no source.

CLI and stdio MCP surfaces for validation, schemas, fixtures, project inventory, evaluation, and six static method prompts.
Project-owned pack matrices with informative, non-gating coverage, plus an experimental graph-composition workflow with its own matrices.
Opt-in JSONL evaluation records and a deterministic reviewed-set lock that detects drift. Both are runtime conventions, not JPS audit or approval formats.

Download latest release Build with packs Connect an MCP client

Reference runtime · one implementation among peers · source

Open source · Apache-2.0 · experimental, claims no conformance

clean-room Python evaluator

A second evaluator, written from the specification text alone inside an information barrier and published with its interpretation log, clean-room protocol, and agreement harness. It exists to test whether the prose pins the semantics: where two independent readings diverge, the divergence locates an ambiguity in the specification rather than a defect in either reader. It claims no JPS conformance of any kind.

Agreement evidence · not a conformance claim

Two implementations, one author. Both listings above trace to the same maintainer's direction, so their agreement corroborates that the specification is precise — it is not independent evidence of interoperability, and the project does not present it as such. See governance for the interim review regime this sits under.

Companion projects

These projects exercise the implementation around JPS. They are not additional JPS implementations, and none of their interfaces or artifacts becomes part of the specification by being listed here.

Cloneable sandbox · Slack-app source · non-normative

judgment-pack demo

A browser workspace and enterprise-shaped synthetic project with the runtime pre-wired over MCP, plus a self-serve Slack implementation. It demonstrates pack authoring and matrices, evaluation and honest refusal, experimental graphs, attested inputs, project-owned evaluation records, and reviewed-set drift detection. The runtime computes every disposition; the model may gather inputs, draft, and narrate, but cannot change the runtime result. Use synthetic, non-sensitive material only.

Demo material · never authorization or production guidance

Open source · research preview · not integrated with the runtime

open reference gateway

The gateway acquires JSON results from operator-configured sources, content-addresses them, signs version-2 receipts with Ed25519, chains them per session, and seals the final count. A verifier with a separately pinned public key can check a store against the gateway-held registry. This is a localhost-only, single-operator reference with no authentication, high availability, or key rotation. It proves byte-lineage, never truth, source identity, authorization, or production readiness.

Receipt and seal specification · frozen corpus

Adding an implementation

This list is open to independent tools tested against the public conformance artifacts. Presence here does not confer certification, official-validator status, endorsement, or authority over the specification. A submission should say which class and exact version it claims, if any, and link to the complete claim rather than asking this project to restate it.