Sequence

Sequence is a web3 developer platform (0xsequence, now part of Polygon Labs) for building blockchain applications: smart-contract wallets, a universal crypto payments and swap layer, a real-time multi-chain Indexer with balances, token prices, contract events and webhooks, plus Metadata, Marketplace, Transactions (Relayer) and Analytics APIs. Its backend APIs are webrpc-generated (POST /rpc/{Service}/{Method}) authenticated with a project access key and secret JWT, and it ships first-party SDKs for TypeScript, Go, Unity, Unreal, Kotlin and Swift plus a CLI. Backed by a16z and Polychain.

Sequence publishes 5 API contracts indexed on the APIs.io network, including Analytics API, Marketplace API, Public API, and 2 more. Tagged areas include Company, Web3, Blockchain, Wallets, and Payments.

The Sequence catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

Sequence’s developer surface includes documentation, API reference, signup flow, support, engineering blog, pricing, changelog, and 23 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

41.5/100 developing ▬ flat Agent 27/100 agent aware Front door AI 1/6 silent Heartbeat 11/100 dormant saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

7 published contracts 2 Agent Skills

Company Web3 Blockchain Wallets Payments Cryptocurrency Indexer NFT Developer Platform Gaming

Kin Score

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

Composite quality — 41.5/100 · developing

Contract Quality 10.1 / 19

Developer Ergonomics 8.8 / 15

Access Clarity 1.6 / 15

Operational Transparency 4.1 / 10

Contract Governance 1.6 / 9

Discoverability 5.9 / 8

Regulatory Posture 2.3 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 27/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 4 / 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 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Payments 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
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
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
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document

5 more unmet checks in the Agent Readiness table above.

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

Access Clarity scores 10.5 — up to +17.9 composite points
Contract Quality scores 53.7 — up to +11.6 composite points
Contract Governance scores 18.2 — up to +9.8 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/sequence/apis.yml: open an issue on github.com/api-evangelist/sequence 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.

Sequence Analytics API

The Analytics API from Sequence — 177 operation(s) for analytics.

Sequence Marketplace API

The Marketplace API from Sequence — 34 operation(s) for marketplace.

Sequence Public API

Endpoints accessible by passing your project-access-key in the header. This is injected whenever you login automatically.

Sequence Rpc API

The Rpc API from Sequence — 32 operation(s) for rpc.

Sequence Secret API

Endpoints that require a Sequence service token intended to be secret. You can manually generate one on Sequence Builder and pass it as a Bearer Token.

Open Collections 5

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

Api Analytics API

OPEN COLLECTION

Api Analytics Marketplace API

OPEN COLLECTION

Api Analytics public API

OPEN COLLECTION

Api Analytics Rpc API

OPEN COLLECTION

Api Analytics secret API

OPEN COLLECTION

Agent Skills 2

Packaged agent skills for driving this provider's APIs from an AI assistant.

sequence-read-token-balances

AGENT SKILL

sequence-watch-onchain-events

AGENT SKILL

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Sequence Indexer Webhooks

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Sequence API Rules

43 rules · 39 errors 3 warnings 1 info

SPECTRAL

OpenAPI Overlays 7

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Sequence Analytics Overlay

2 actions · update · sequence-analytics.json

DERIVED

Sequence Builder Overlay

2 actions · update · sequence-builder.json

DERIVED

Sequence Indexer Overlay

2 actions · update · sequence-indexer.json

DERIVED

Sequence Infrastructure Overlay

2 actions · update · sequence-infrastructure.json

DERIVED

Sequence Marketplace Overlay

2 actions · update · sequence-marketplace.json

DERIVED

Sequence Metadata Overlay

2 actions · update · sequence-metadata.json

DERIVED

Sequence Transactions Overlay

2 actions · update · sequence-transactions.json

DERIVED

Scroll for all 7

Security Posture 2

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

Sequence Authentication

apiKey/http · 2 schemes

SECURITY

Sequence Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

SignUp

SignUp

Sandbox

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

X-MCPServerCandidate

X-MCPServerCandidate

WellKnown

WellKnown

AgentSkill

AgentSkill

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Components

Conventions

ErrorCatalog

Conformance

Lifecycle

DataModel

Webhooks

Scroll for all 7

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

CLI

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 4

Status, limits, changes, and where to get help

Support

HelpCenter

StatusPage

ChangeLog

Commercial 1

Pricing, plans, and the legal terms of use

Pricing

Pricing

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: sequence
name: Sequence
description: 'Sequence is a web3 developer platform (0xsequence, now part of Polygon Labs) for building blockchain applications:
  smart-contract wallets, a universal crypto payments and swap layer, a real-time multi-chain Indexer with balances, token
  prices, contract events and webhooks, plus Metadata, Marketplace, Transactions (Relayer) and Analytics APIs. Its backend
  APIs are webrpc-generated (POST /rpc/{Service}/{Method}) authenticated with a project access key and secret JWT, and it
  ships first-party SDKs for TypeScript, Go, Unity, Unreal, Kotlin and Swift plus a CLI. Backed by a16z and Polychain.'
url: https://raw.githubusercontent.com/api-evangelist/sequence/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- a16z
- polychain
x-tier: stub
x-tier-reason: portfolio-lead
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  - sandbox
  generated: '2026-11-06'
  method: derived
image: https://sequence.xyz/favicon.ico
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
x-docs-platform: mintlify
x-docs-platform-confidence: medium
x-docs-platform-checked: 2026-10-04
x-docs-hosting: vercel
tags:
- Company
- Web3
- Blockchain
- Wallets
- Payments
- Cryptocurrency
- Indexer
- NFT
- Developer Platform
- Gaming
tags_raw:
- Company
- Web3
- Blockchain
- Wallets
- Payments
- Crypto
- Indexer
- NFT
- Developer Platform
- Gaming
apis:
- aid: sequence:sequence-analytics-api
  name: Sequence Analytics API
  description: The Analytics API from Sequence — 177 operation(s) for analytics.
  humanURL: https://docs.sequence.xyz/api-references/indexer/overview
  baseURL: https://mainnet-indexer.sequence.app
  tags:
  - Analytics
  properties:
  - type: OpenAPI
    url: openapi/sequence-analytics-api-openapi.yml
  - type: Webhooks
    url: asyncapi/sequence-indexer-webhooks.yml
- aid: sequence:sequence-marketplace-api
  name: Sequence Marketplace API
  description: The Marketplace API from Sequence — 34 operation(s) for marketplace.
  humanURL: https://docs.sequence.xyz/api-references/indexer/overview
  baseURL: https://mainnet-indexer.sequence.app
  tags:
  - Marketplace
  properties:
  - type: OpenAPI
    url: openapi/sequence-marketplace-api-openapi.yml
  - type: Webhooks
    url: asyncapi/sequence-indexer-webhooks.yml
- aid: sequence:sequence-public-api
  name: Sequence Public API
  description: Endpoints accessible by passing your project-access-key in the header. This is injected whenever you login
    automatically.
  humanURL: https://docs.sequence.xyz/api-references/indexer/overview
  baseURL: https://mainnet-indexer.sequence.app
  tags:
  - Public
  tags_raw:
  - public
  properties:
  - type: OpenAPI
    url: openapi/sequence-public-api-openapi.yml
  - type: Webhooks
    url: asyncapi/sequence-indexer-webhooks.yml
- aid: sequence:sequence-rpc-api
  name: Sequence Rpc API
  description: The Rpc API from Sequence — 32 operation(s) for rpc.
  humanURL: https://docs.sequence.xyz/api-references/indexer/overview
  baseURL: https://mainnet-indexer.sequence.app
  tags:
  - RPC
  tags_raw:
  - Rpc
  properties:
  - type: OpenAPI
    url: openapi/sequence-rpc-api-openapi.yml
  - type: Webhooks
    url: asyncapi/sequence-indexer-webhooks.yml
- aid: sequence:sequence-secret-api
  name: Sequence Secret API
  description: Endpoints that require a Sequence service token intended to be secret. You can manually generate one on Sequence
    Builder and pass it as a Bearer Token.
  humanURL: https://docs.sequence.xyz/api-references/indexer/overview
  baseURL: https://mainnet-indexer.sequence.app
  tags:
  - Secret
  tags_raw:
  - secret
  properties:
  - type: OpenAPI
    url: openapi/sequence-secret-api-openapi.yml
  - type: Webhooks
    url: asyncapi/sequence-indexer-webhooks.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Overlay
  url: overlays/sequence-analytics-overlay.yaml
- type: Website
  url: https://sequence.xyz
- type: DeveloperPortal
  url: https://sequence.build
- type: Documentation
  url: https://docs.sequence.xyz
- type: APIReference
  url: https://docs.sequence.xyz/api-references/overview
- type: SignUp
  url: https://sequence.build
- type: Support
  url: https://support.sequence.xyz/en/
- type: HelpCenter
  url: https://support.sequence.xyz/en/
- type: Blog
  url: https://sequence.xyz/blog
- type: GitHubOrganization
  url: https://github.com/0xsequence
- type: Pricing
  url: https://sequence.xyz/pricing
- type: StatusPage
  url: lifecycle/sequence-lifecycle.yml
- type: ChangeLog
  url: changelog/sequence-changelog.yml
- type: Packages
  url: packages/sequence-packages.yml
- type: SDKs
  url: packages/sequence-packages.yml
- type: CLI
  url: cli/sequence-cli.yml
- type: Components
  url: components/sequence-components.yml
- type: LLMsTxt
  url: llms/sequence-llms.txt
- type: X-MCPServerCandidate
  url: mcp/sequence-mcp.yml
  note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list derived
    from the published API contracts, not an existing server. The scorer already read the manifest and reported mcp_server
    correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
- type: WellKnown
  url: well-known/sequence-well-known.yml
- type: Authentication
  url: authentication/sequence-authentication.yml
- type: DomainSecurity
  url: security/sequence-domain-security.yml
- type: Conventions
  url: conventions/sequence-conventions.yml
- type: ErrorCatalog
  url: errors/sequence-problem-types.yml
- type: Conformance
  url: conformance/sequence-conformance.yml
- type: Lifecycle
  url: lifecycle/sequence-lifecycle.yml
- type: DataModel
  url: data-model/sequence-data-model.yml
- type: Sandbox
  url: sandbox/sequence-sandbox.yml
- type: Webhooks
  url: asyncapi/sequence-indexer-webhooks.yml
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 30
  pass: local-v1

Sequence API — frequently asked questions

Does Sequence have an API?

Yes. APIs.io lists 5 APIs from Sequence, including Sequence Analytics API, Sequence Marketplace API and Sequence Public API, and 2 more.

Is there an OpenAPI specification for the Sequence API?

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

How do I authenticate with the Sequence API?

Sequence uses bearer-token authentication (apiKey/http · 2 schemes). The details are profiled on APIs.io as Sequence Authentication.

Is the Sequence API ready for AI agents?

Sequence has a Kin Score of 41.5 out of 100 (developing) and an Agent Readiness score of 26.9 (agent-aware), scored by API Evangelist on 2026-11-06.

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