S2 Dev

S2 ("Stream Store") is the API for unlimited, durable, real-time streams. Where object storage deals with blobs, S2 provides append-able, ordered record streams that can be tailed in real time and replayed from any retained point. Core data-plane operations are append, read, and check-tail; the control plane manages accounts, basins (stream namespaces), streams, scoped access tokens, locations, and metrics. It targets agent session logs, live views and build logs, event sourcing and sync, data feeds, resumable LLM token streaming, and observability. Access is over a REST/JSON + Protobuf HTTP API, an S2S binary protocol over HTTP/2, SSE tailing, first-party TypeScript, Python, Go, and Rust SDKs, a CLI, and a Terraform provider. S2 is a Y Combinator-backed company.

S2 Dev publishes 6 APIs on the APIs.io network, including access-tokens API, basins API, locations API, and 3 more. Tagged areas include Company, Streaming, Real-Time, Event Streaming, and Durable Storage.

S2 Dev’s developer surface includes authentication, documentation, API reference, getting-started guide, support, engineering blog, pricing, and 31 more developer resources.

🌐 Visit website 📡 Source on GitHub

60.1/100 strong ▬ flat Agent 33/100 agent ready saas Full breakdown ↓
scored 2026-09-06 · rubric v0.19.0

1 APIs

Company Streaming Real-Time Event StreamingDurable StorageMessage StreamingData Feeds Observability Developer Tools Infrastructure

Kin Score

Kin Score How this is scored →
scored 2026-09-06 · rubric v0.19.0

Composite quality — 60.1/100 · strong

Contract Quality 13.9 / 25

Developer Ergonomics 16.1 / 20

Access Clarity 12.1 / 20

Operational Transparency 9.9 / 13

Contract Governance 0.5 / 12

Discoverability 7.6 / 10

Agent readiness — 33/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 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 4 / 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

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 github.com/api-evangelist/s2-dev: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 6

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

Rate Limits 1

Documented rate limits and quota policies.

AGENTIC

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

GettingStarted

SignUp

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

WellKnown

WellKnown

LLMsTxt

LLMsTxt

X-MCPServerCandidate

X-MCPServerCandidate

AgentSkill

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Lifecycle

Conventions

Idempotency

ErrorCatalog

DataModel

Conformance

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

CLI

Access & Security 7

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

Authentication

Security

TrustCenter

Compliance

SecurityTxt

Scroll for all 7

Operate 4

Status, limits, changes, and where to get help

Support

StatusPage

ChangeLog

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 1

The organization behind the API

Blog

Blog

Other 2

Properties that don't map to a standard resource type

APICatalog

APICatalog

Overlay

Overlay

Source (apis.yml)

aid: s2-dev
name: S2 Dev
description: S2 ("Stream Store") is the API for unlimited, durable, real-time streams. Where object storage deals with blobs,
  S2 provides append-able, ordered record streams that can be tailed in real time and replayed from any retained point. Core
  data-plane operations are append, read, and check-tail; the control plane manages accounts, basins (stream namespaces),
  streams, scoped access tokens, locations, and metrics. It targets agent session logs, live views and build logs, event sourcing
  and sync, data feeds, resumable LLM token streaming, and observability. Access is over a REST/JSON + Protobuf HTTP API,
  an S2S binary protocol over HTTP/2, SSE tailing, first-party TypeScript, Python, Go, and Rust SDKs, a CLI, and a Terraform
  provider. S2 is a Y Combinator-backed company.
url: https://raw.githubusercontent.com/api-evangelist/s2-dev/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
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
  - rate-limits
  - security
  - sandbox
  generated: '2026-09-03'
  method: derived
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
image: https://avatars.githubusercontent.com/u/136030139?v=4
tags:
- Company
- Streaming
- Real-Time
- Event Streaming
- Durable Storage
- Message Streaming
- Data Feeds
- Observability
- Developer Tools
- Infrastructure
apis:
- aid: s2-dev:s2-dev-access-tokens-api
  name: S2 Dev access-tokens API
  description: Manage access tokens
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Access Tokens
  tags_raw:
  - access-tokens
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-access-tokens-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
- aid: s2-dev:s2-dev-basins-api
  name: S2 Dev basins API
  description: Manage basins
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Basins
  tags_raw:
  - basins
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-basins-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
- aid: s2-dev:s2-dev-locations-api
  name: S2 Dev locations API
  description: Manage locations
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Locations
  tags_raw:
  - locations
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-locations-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
- aid: s2-dev:s2-dev-metrics-api
  name: S2 Dev metrics API
  description: Usage metrics and data.
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Metrics
  tags_raw:
  - metrics
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-metrics-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
- aid: s2-dev:s2-dev-records-api
  name: S2 Dev records API
  description: Manage records
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Records
  tags_raw:
  - records
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-records-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
- aid: s2-dev:s2-dev-streams-api
  name: S2 Dev streams API
  description: Manage streams
  humanURL: https://s2.dev/docs/api
  baseURL: https://a.s2.dev/v1
  tags:
  - Streams
  tags_raw:
  - streams
  properties:
  - type: OpenAPI
    url: openapi/s2-dev-streams-api-openapi.yml
  - type: Protobuf
    url: grpc/s2-dev-s2.proto
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 26
  pass: local-v1
common:
- type: VulnerabilityDisclosure
  url: security/s2-dev-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/s2-dev-domain-security.yml
- type: AgenticAccess
  url: agentic-access/s2-dev-agentic-access.yml
- type: Authentication
  url: authentication/s2-dev-authentication.yml
- type: Security
  url: https://s2.dev/docs/platform/security
- type: TrustCenter
  url: security/s2-dev-trust-center.yml
- type: Compliance
  url: https://s2.dev/docs/platform/security
- type: DeveloperPortal
  url: https://s2.dev/docs
- type: Documentation
  url: https://s2.dev/docs
- type: APIReference
  url: https://s2.dev/docs/api
- type: GettingStarted
  url: https://s2.dev/docs/quickstart
- type: Support
  url: mailto:hi@s2.dev
- type: Blog
  url: https://s2.dev/blog
- type: GitHubOrganization
  url: https://github.com/s2-streamstore
- type: Pricing
  url: https://s2.dev/pricing
- type: SignUp
  url: https://s2.dev/dashboard
- type: TermsOfService
  url: https://s2.dev/terms
- type: PrivacyPolicy
  url: https://s2.dev/privacy
- type: StatusPage
  url: https://status.s2.dev
- type: Packages
  url: packages/s2-dev-packages.yml
- type: SDKs
  url: packages/s2-dev-packages.yml
- type: CLI
  url: cli/s2-dev-cli.yml
- type: Sandbox
  url: sandbox/s2-dev-sandbox.yml
- type: ChangeLog
  url: changelog/s2-dev-changelog.yml
- type: Lifecycle
  url: lifecycle/s2-dev-lifecycle.yml
- type: RateLimits
  url: rate-limits/s2-dev-rate-limits.yml
- type: Conventions
  url: conventions/s2-dev-conventions.yml
- type: Idempotency
  url: conventions/s2-dev-conventions.yml
- type: ErrorCatalog
  url: errors/s2-dev-problem-types.yml
- type: DataModel
  url: data-model/s2-dev-data-model.yml
- type: Conformance
  url: conformance/s2-dev-conformance.yml
- type: WellKnown
  url: well-known/s2-dev-well-known.yml
- type: SecurityTxt
  url: well-known/s2-dev-security.txt
- type: APICatalog
  url: well-known/s2-dev-api-catalog.json
- type: LLMsTxt
  url: llms/s2-dev-llms.txt
- type: Overlay
  url: overlays/s2-dev-openapi-overlay.yaml
- type: X-MCPServerCandidate
  url: mcp/s2-dev-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: AgentSkill
  url: skills/_index.yml

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