Sequin

Sequin is an open-source Postgres change data capture (CDC) engine that streams Postgres rows and changes to streams, queues, and search indexes - Kafka, SQS, SNS, Kinesis, Redis, NATS, RabbitMQ, Elasticsearch, Typesense, GCP Pub/Sub, Azure Event Hubs, and HTTP/webhook endpoints - with exactly-once processing, backfills, and low-latency delivery. Sequin is self-hostable and also available as Sequin Cloud. Resources are configured declaratively via a sequin.yaml file or programmatically through the Management API; consumers can pull changes over HTTP via the Sequin Stream sink.

Sequin publishes 5 API contracts indexed on the APIs.io network, including Backfills API, HTTP Endpoints API, Postgres Databases API, and 2 more. Tagged areas include Change Data Capture, PostgreSQL, Streaming, Open Source, and Data Pipeline.

The Sequin catalog on APIs.io includes 1 Spectral governance ruleset.

Sequin’s developer surface includes authentication, documentation, engineering blog, and 8 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

27.4/100 thin ▬ flat Agent 19/100 agent aware Front door AI 1/6 silent Heartbeat 8/100 dormant saas Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

1 published contract

Change Data Capture PostgreSQL Streaming Open Source Data Pipeline

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 27.4/100 · thin

Contract Quality 9.1 / 19

Developer Ergonomics 4.7 / 15

Access Clarity 1.0 / 15

Operational Transparency 1.2 / 10

Contract Governance 1.2 / 9

Discoverability 5.0 / 8

Regulatory Posture 0.9 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 19/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 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 Ask about this →
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) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document Ask about this →

10 more unmet checks in the Agent Readiness table above.

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

Access Clarity scores 6.4 — up to +18.7 composite points Ask about this →
Developer Ergonomics scores 31.0 — up to +13.8 composite points Ask about this →
Contract Quality scores 48.7 — up to +12.8 composite points Ask about this →

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.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

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/sequin-io/apis.yml: open an issue on github.com/api-evangelist/sequin-io 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 →

Standards implemented 1

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.

OpenAPI

measured — observed by APIs.io (published)

APIs 5

Individual APIs this provider publishes, each with its own machine-readable definition.

Sequin Backfills API

Replay existing Postgres rows into a sink.

Sequin HTTP Endpoints API

Reusable HTTP endpoint destinations used by webhook sinks.

Sequin Postgres Databases API

Source Postgres database connections Sequin replicates from.

Sequin Sink Consumers API

Destinations that stream Postgres changes to external systems.

Sequin Stream Pull API

HTTP pull consumption for the Sequin Stream sink.

Open Collections 6

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Sequin Management Backfills API

OPEN COLLECTION

Sequin Management Backfills HTTP Endpoints API

OPEN COLLECTION

Sequin Management Backfills Postgres Databases API

OPEN COLLECTION

Sequin Management Backfills Sink Consumers API

OPEN COLLECTION

Sequin Management Backfills Stream Pull API

OPEN COLLECTION

Sequin Management API

OPEN COLLECTION

Sequin API pricing

Not yet checked against Sequin's own pricing page. Compiled by API Evangelist on 2026-07-01 from sequinstream.com/; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Open Source (Self-Hosted) free	—
Sequin Cloud - Free free	—
Sequin Cloud - Usage usage	—
Enterprise / Custom enterprise	—

Plan details, limits and sources →

Rate limits

Management API Requests: not published requests
Self-Hosted Throughput: hardware-bound (~50k ops/sec, ~40 MB/s benchmarked) operations
Cloud Throughput Allowance: per plan records

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

Pricing Plans 1

Published pricing tiers and plan structures.

Sequin Plans Pricing

4 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Sequin Rate Limits

5 limits

RATE LIMITS

FinOps 1

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

Sequin Finops

FINOPS

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

Sequin API Rules

63 rules · 60 error-severity 2 warn-severity 1 info-severity

SPECTRAL

Security Posture 2

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

Sequin Authentication

http · 1 scheme

SECURITY

Sequin Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

Sequin Agentic Access

25 operations · 16 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Source (apis.yml)

aid: sequin-io
url: https://raw.githubusercontent.com/api-evangelist/sequin-io/refs/heads/main/apis.yml
name: Sequin
kind: company
description: Sequin is an open-source Postgres change data capture (CDC) engine that streams Postgres rows and changes to
  streams, queues, and search indexes - Kafka, SQS, SNS, Kinesis, Redis, NATS, RabbitMQ, Elasticsearch, Typesense, GCP Pub/Sub,
  Azure Event Hubs, and HTTP/webhook endpoints - with exactly-once processing, backfills, and low-latency delivery. Sequin
  is self-hostable and also available as Sequin Cloud. Resources are configured declaratively via a sequin.yaml file or programmatically
  through the Management API; consumers can pull changes over HTTP via the Sequin Stream sink.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-13'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/sequin-io.png
tags:
- Change Data Capture
- PostgreSQL
- Streaming
- Open Source
- Data Pipeline
tags_raw:
- Change Data Capture
- Postgres
- Streaming
- Open Source
- Data Pipeline
- Open-Source
created: '2026-07-01'
modified: '2026-07-01'
specificationVersion: '0.23'
apis:
- aid: sequin-io:sequin-io-backfills-api
  name: Sequin Backfills API
  description: Replay existing Postgres rows into a sink.
  humanURL: https://sequinstream.com/docs/management-api/sink-consumers/list
  baseURL: https://api.sequinstream.com/api
  tags:
  - backfills
  tags_raw:
  - Backfills
  properties:
  - type: OpenAPI
    url: openapi/sequin-io-backfills-api-openapi.yml
  - type: Documentation
    url: https://sequinstream.com/docs/management-api/introduction
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/sink-consumers/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/postgres_databases/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/http-endpoints/get
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/backfills/create
  - type: Documentation
    url: https://sequinstream.com/docs/reference/sinks/sequin-stream
- aid: sequin-io:sequin-io-http-endpoints-api
  name: Sequin HTTP Endpoints API
  description: Reusable HTTP endpoint destinations used by webhook sinks.
  humanURL: https://sequinstream.com/docs/management-api/sink-consumers/list
  baseURL: https://api.sequinstream.com/api
  tags:
  - HTTP Endpoints
  properties:
  - type: OpenAPI
    url: openapi/sequin-io-http-endpoints-api-openapi.yml
  - type: Documentation
    url: https://sequinstream.com/docs/management-api/introduction
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/sink-consumers/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/postgres_databases/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/http-endpoints/get
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/backfills/create
  - type: Documentation
    url: https://sequinstream.com/docs/reference/sinks/sequin-stream
- aid: sequin-io:sequin-io-postgres-databases-api
  name: Sequin Postgres Databases API
  description: Source Postgres database connections Sequin replicates from.
  humanURL: https://sequinstream.com/docs/management-api/sink-consumers/list
  baseURL: https://api.sequinstream.com/api
  tags:
  - Postgres Databases
  properties:
  - type: OpenAPI
    url: openapi/sequin-io-postgres-databases-api-openapi.yml
  - type: Documentation
    url: https://sequinstream.com/docs/management-api/introduction
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/sink-consumers/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/postgres_databases/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/http-endpoints/get
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/backfills/create
  - type: Documentation
    url: https://sequinstream.com/docs/reference/sinks/sequin-stream
- aid: sequin-io:sequin-io-sink-consumers-api
  name: Sequin Sink Consumers API
  description: Destinations that stream Postgres changes to external systems.
  humanURL: https://sequinstream.com/docs/management-api/sink-consumers/list
  baseURL: https://api.sequinstream.com/api
  tags:
  - Sink Consumers
  properties:
  - type: OpenAPI
    url: openapi/sequin-io-sink-consumers-api-openapi.yml
  - type: Documentation
    url: https://sequinstream.com/docs/management-api/introduction
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/sink-consumers/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/postgres_databases/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/http-endpoints/get
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/backfills/create
  - type: Documentation
    url: https://sequinstream.com/docs/reference/sinks/sequin-stream
- aid: sequin-io:sequin-io-stream-pull-api
  name: Sequin Stream Pull API
  description: HTTP pull consumption for the Sequin Stream sink.
  humanURL: https://sequinstream.com/docs/management-api/sink-consumers/list
  baseURL: https://api.sequinstream.com/api
  tags:
  - Stream Pull
  properties:
  - type: OpenAPI
    url: openapi/sequin-io-stream-pull-api-openapi.yml
  - type: Documentation
    url: https://sequinstream.com/docs/management-api/introduction
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/sink-consumers/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/postgres_databases/list
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/http-endpoints/get
  - type: APIReference
    url: https://sequinstream.com/docs/management-api/backfills/create
  - type: Documentation
    url: https://sequinstream.com/docs/reference/sinks/sequin-stream
common:
- type: AgenticAccess
  url: agentic-access/sequin-io-agentic-access.yml
- type: DomainSecurity
  url: security/sequin-io-domain-security.yml
- type: Authentication
  url: authentication/sequin-io-authentication.yml
- type: GitHubOrganization
  url: https://github.com/sequinstream
- type: LinkedIn
  url: https://www.linkedin.com/company/sequin-io
- type: Website
  url: https://sequinstream.com
- type: Documentation
  url: https://sequinstream.com/docs
- type: Plans
  url: plans/sequin-io-plans-pricing.yml
- type: RateLimits
  url: rate-limits/sequin-io-rate-limits.yml
- type: FinOps
  url: finops/sequin-io-finops.yml
- url: https://blog.sequinstream.com/feed
  type: Blog
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Sequin API — frequently asked questions

Does Sequin have an API?

Yes. APIs.io lists 5 APIs from Sequin, including Sequin Backfills API, Sequin HTTP Endpoints API and Sequin Postgres Databases API, and 2 more.

Is there an OpenAPI specification for the Sequin API?

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

How do I authenticate with the Sequin API?

Sequin uses bearer-token authentication (http · 1 scheme). The details are profiled on APIs.io as Sequin Authentication.

How much does the Sequin API cost?

APIs.io lists 4 pricing plans for Sequin, with each plan's price, limits and inclusions under Pricing on this page.

Is the Sequin API ready for AI agents?

Sequin has a Kin Score of 27.4 out of 100 (thin) and an Agent Readiness score of 19.0 (agent-aware), scored by API Evangelist on 2026-11-13.

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