Confluent Schema Registry

Confluent Schema Registry is the open-source serving layer for schema metadata used in Apache Kafka data pipelines. It exposes a RESTful interface for storing and retrieving Avro, JSON Schema, and Protobuf schemas, manages schema evolution through configurable compatibility rules (BACKWARD, FORWARD, FULL, and transitive variants), supports schema references and contexts, and integrates with Kafka producers and consumers via shipped serializers and deserializers. Schema Registry is distributed under the Confluent Community License and is a core component of both Confluent Platform and Confluent Cloud.

Confluent Schema Registry publishes 5 API contracts indexed on the APIs.io network, including Compatibility API, Mode API, Schemas API, and 2 more. Tagged areas include Apache Kafka, Avro, Compatibility, Confluent, and Data Governance.

The Confluent Schema Registry catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

Confluent Schema Registry’s developer surface includes documentation, getting-started guide, API reference, GitHub presence, engineering blog, pricing, and 13 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

33.3/100 thin ▬ flat Agent 25/100 agent aware saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemium

1 published contract 12 Agent Skills

Apache Kafka Avro CompatibilityConfluentData Governance Data Streaming JSON Schema Open Source Protobuf REST Schema Evolution Schema Registry

What this lets a business do 1

Business capabilities this provider's published APIs can perform, derived from its own contracts. Browse all capabilities →

Information & Data Management

BC-610

CompatibilitySchemasSubjects

POST /subjects/{subject}/versions POST /subjects/{subject} GET /config POST /compatibility/subjects/{subject}/versions/{version}

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 33.3/100 · thin

Contract Quality 8.6 / 19

Developer Ergonomics 5.6 / 15

Access Clarity 2.8 / 15

Operational Transparency 2.3 / 10

Contract Governance 1.2 / 9

Discoverability 4.8 / 8

Regulatory Posture 2.5 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 25/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document

9 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 18.4 — up to +16.3 composite points
Contract Quality scores 45.7 — up to +13.6 composite points
Developer Ergonomics scores 37.4 — up to +12.5 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/confluent-schema-registry/apis.yml: open an issue on github.com/api-evangelist/confluent-schema-registry to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Buf Schema Registry (public Protocol Buffers modules, gRPC / ConnectRPC schema publishers)	undeclared	-	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 4

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Avro

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

JSON Schema

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

REST

AGENT SKILL

stale-expectations

AGENT SKILL

trigger-overlap

AGENT SKILL

Scroll for all 12

Confluent Schema Registry API pricing

Not yet checked against Confluent Schema Registry's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against Confluent Schema Registry's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

Confluent Schema Registry Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Confluent Schema Registry Rate Limits

5 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

Confluent Schema Registry

SLA

FinOps 1

Cost, billing, and metering signals for API financial operations.

Confluent Schema Registry Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Confluent Schema Registry Context

0 classes · 10 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Confluent Schema Registry — jsonschema rules

5 rules · 3 warnings 2 info

SPECTRAL

Confluent Schema Registry API Rules

10 rules · 4 errors 6 warnings

SPECTRAL

JSON Schema 1

Standalone JSON Schema definitions for this provider's data models.

Confluent Schema Registry Schema

7 properties

JSON SCHEMA

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Confluent Schema Registry Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Confluent Schema Registry Vulnerability Disclosure

security.txt · contact published

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Confluent Schema Registry Agentic Access

21 operations · 9 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

AgentSkills

AgentSkills

LlmsText

LlmsText

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

JSONLD

JSONLD

Spectral

Spectral

Build 1

SDKs, sample code, and the tooling you integrate with

GitHub

GitHub

Access & Security 2

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Plans

FinOps

License

Pricing

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

aid: confluent-schema-registry
name: Confluent Schema Registry
description: Confluent Schema Registry is the open-source serving layer for schema metadata used in Apache Kafka data pipelines.
  It exposes a RESTful interface for storing and retrieving Avro, JSON Schema, and Protobuf schemas, manages schema evolution
  through configurable compatibility rules (BACKWARD, FORWARD, FULL, and transitive variants), supports schema references
  and contexts, and integrates with Kafka producers and consumers via shipped serializers and deserializers. Schema Registry
  is distributed under the Confluent Community License and is a core component of both Confluent Platform and Confluent Cloud.
type: Index
deliveryModel:
  model: saas
  license_evidence:
    not_product:
    - confluentinc/schema-registry
  open_source: unknown
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: low
  source:
  - openapi
  - pricing
  - repository-not-product
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: low
  try_now_blocked_by: loopback
  source:
  - plans
  - security
  generated: '2026-11-06'
  method: derived
position: Producing
access: Open Source
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/confluent-schema-registry.png
url: https://raw.githubusercontent.com/api-evangelist/confluent-schema-registry/refs/heads/main/apis.yml
created: '2026-03-26'
modified: '2026-05-19'
specificationVersion: '0.23'
kind: opensource
x-docs-platform: sphinx
x-docs-platform-confidence: medium
x-docs-platform-checked: 2026-09-24
tags:
- Apache Kafka
- Avro
- Compatibility
- Confluent
- Data Governance
- Data Streaming
- JSON Schema
- Open Source
- Protobuf
- REST
- Schema Evolution
- Schema Registry
tags_raw:
- Apache Kafka
- Avro
- Compatibility
- Confluent
- Data Governance
- Data Streaming
- JSON Schema
- Open Source
- Protobuf
- REST
- Schema Evolution
- Schema Registry
- JSON-Schema
- Open-Source
apis:
- aid: confluent-schema-registry:confluent-schema-registry-compatibility-api
  name: Confluent Schema Registry Compatibility API
  description: The Compatibility API from Confluent Schema Registry — 3 operation(s) for compatibility.
  humanURL: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  baseURL: http://localhost:8081
  tags:
  - Compatibility
  properties:
  - type: OpenAPI
    url: openapi/confluent-schema-registry-compatibility-api-openapi.yml
  - type: Documentation
    url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  - type: JSONSchema
    url: json-schema/schema-registry-schema.json
  - type: JSONLD
    url: json-ld/confluent-schema-registry-context.jsonld
  - type: Spectral
    url: rules/confluent-schema-registry-rules.yml
  - type: GitHub
    url: https://github.com/confluentinc/schema-registry
- aid: confluent-schema-registry:confluent-schema-registry-mode-api
  name: Confluent Schema Registry Mode API
  description: The Mode API from Confluent Schema Registry — 1 operation(s) for mode.
  humanURL: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  baseURL: http://localhost:8081
  tags:
  - Mode
  properties:
  - type: OpenAPI
    url: openapi/confluent-schema-registry-mode-api-openapi.yml
  - type: Documentation
    url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  - type: JSONSchema
    url: json-schema/schema-registry-schema.json
  - type: JSONLD
    url: json-ld/confluent-schema-registry-context.jsonld
  - type: Spectral
    url: rules/confluent-schema-registry-rules.yml
  - type: GitHub
    url: https://github.com/confluentinc/schema-registry
- aid: confluent-schema-registry:confluent-schema-registry-schemas-api
  name: Confluent Schema Registry Schemas API
  description: The Schemas API from Confluent Schema Registry — 3 operation(s) for schemas.
  humanURL: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  baseURL: http://localhost:8081
  tags:
  - Schema
  tags_raw:
  - Schemas
  properties:
  - type: OpenAPI
    url: openapi/confluent-schema-registry-schemas-api-openapi.yml
  - type: Documentation
    url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  - type: JSONSchema
    url: json-schema/schema-registry-schema.json
  - type: JSONLD
    url: json-ld/confluent-schema-registry-context.jsonld
  - type: Spectral
    url: rules/confluent-schema-registry-rules.yml
  - type: GitHub
    url: https://github.com/confluentinc/schema-registry
- aid: confluent-schema-registry:confluent-schema-registry-server-api
  name: Confluent Schema Registry Server API
  description: The Server API from Confluent Schema Registry — 1 operation(s) for server.
  humanURL: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  baseURL: http://localhost:8081
  tags:
  - Servers
  tags_raw:
  - Server
  properties:
  - type: OpenAPI
    url: openapi/confluent-schema-registry-server-api-openapi.yml
  - type: Documentation
    url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  - type: JSONSchema
    url: json-schema/schema-registry-schema.json
  - type: JSONLD
    url: json-ld/confluent-schema-registry-context.jsonld
  - type: Spectral
    url: rules/confluent-schema-registry-rules.yml
  - type: GitHub
    url: https://github.com/confluentinc/schema-registry
- aid: confluent-schema-registry:confluent-schema-registry-subjects-api
  name: Confluent Schema Registry Subjects API
  description: The Subjects API from Confluent Schema Registry — 6 operation(s) for subjects.
  humanURL: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  baseURL: http://localhost:8081
  tags:
  - Subjects
  properties:
  - type: OpenAPI
    url: openapi/confluent-schema-registry-subjects-api-openapi.yml
  - type: Documentation
    url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
  - type: JSONSchema
    url: json-schema/schema-registry-schema.json
  - type: JSONLD
    url: json-ld/confluent-schema-registry-context.jsonld
  - type: Spectral
    url: rules/confluent-schema-registry-rules.yml
  - type: GitHub
    url: https://github.com/confluentinc/schema-registry
common:
- type: Plans
  url: plans/confluent-schema-registry-plans-pricing.yml
- type: RateLimits
  url: rate-limits/confluent-schema-registry-rate-limits.yml
- type: FinOps
  url: finops/confluent-schema-registry-finops.yml
- type: CapabilityMap
  url: capabilities/confluent-schema-registry-capability-edges.yml
  name: Confluent Schema Registry Business Capability Map
- type: AgenticAccess
  url: agentic-access/confluent-schema-registry-agentic-access.yml
- type: VulnerabilityDisclosure
  url: security/confluent-schema-registry-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/confluent-schema-registry-domain-security.yml
- name: Agent Skills
  url: https://github.com/confluentinc/agent-skills
  type: AgentSkills
- type: Website
  url: https://www.confluent.io/
- type: Documentation
  url: https://docs.confluent.io/platform/current/schema-registry/
- type: GettingStarted
  url: https://docs.confluent.io/platform/current/schema-registry/develop/using.html
- type: APIReference
  url: https://docs.confluent.io/platform/current/schema-registry/develop/api.html
- type: GitHub
  url: https://github.com/confluentinc/schema-registry
- type: License
  url: https://www.confluent.io/confluent-community-license/
- type: Blog
  url: https://www.confluent.io/blog/
- type: Pricing
  url: https://www.confluent.io/pricing/
- type: JSONLD
  url: json-ld/confluent-schema-registry-context.jsonld
- type: Spectral
  url: rules/confluent-schema-registry-rules.yml
- type: Integrations
  url: https://www.confluent.io/partner/
- type: LlmsText
  url: https://docs.confluent.io/llms.txt
integrations:
- name: Become a Partner
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
x-parent: confluent
x-relationship: product

Confluent Schema Registry API — frequently asked questions

Does Confluent Schema Registry have an API?

Yes. APIs.io lists 5 APIs from Confluent Schema Registry, including Confluent Schema Registry Compatibility API, Confluent Schema Registry Mode API and Confluent Schema Registry Schemas API, and 2 more.

Is there an OpenAPI specification for the Confluent Schema Registry API?

Yes. APIs.io indexes 5 OpenAPI specifications for Confluent Schema Registry, each linked for download from this page.

How much does the Confluent Schema Registry API cost?

APIs.io lists 3 pricing plans for Confluent Schema Registry, with each plan's price, limits and inclusions under Pricing on this page.

Is the Confluent Schema Registry API ready for AI agents?

Confluent Schema Registry has a Kin Score of 33.3 out of 100 (thin) and an Agent Readiness score of 25.1 (agent-aware), scored by API Evangelist on 2026-11-06.

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