Substructure

Substructure provides a cloud‑native agent harness called subs that enables developers to run unprivileged agents locally or as a client‑server system. It offers a hosted deployment, integrates with MCP servers for tool access, and supports a variety of LLM back‑ends. The platform includes extensive documentation, pricing details, llms.txt configuration, and open‑source tooling on GitHub. Substructure aims to simplify building AI‑driven workflows with secure, sandboxed execution.

Substructure is listed with 1 API on the APIs.io network. Tagged areas include Company, Artificial Intelligence, Agents, Cloud-Native, and Automation.

The Substructure catalog on APIs.io includes 1 event-driven AsyncAPI specification, 1 JSON-LD context, and 1 Spectral governance ruleset.

Substructure’s developer surface includes authentication, documentation, getting-started guide, pricing, engineering blog, support, and 21 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

42.3/100 developing ▲ 8.5 Agent 22/100 agent aware Heartbeat 61/100 alive Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

1 API

Company Artificial Intelligence Agents Cloud-Native Automation

Kin Score

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

Composite quality — 42.3/100 · developing

Contract Quality 7.7 / 21

Developer Ergonomics 8.5 / 17

Access Clarity 9.8 / 17

Operational Transparency 1.3 / 11

Contract Governance 2.2 / 10

Discoverability 6.2 / 9

Regulatory Posture 2.6 / 15

Agent readiness — 22/100 · 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 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 6 / 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 5 / 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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% 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 →
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author 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 →
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented) Ask about this →

9 more unmet checks in the Agent Readiness table above.

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

Contract Quality scores 36.1 — up to +16.0 composite points Ask about this →
Operational Transparency scores 11.9 — up to +11.5 composite points Ask about this →
Developer Ergonomics scores 50.0 — up to +10.0 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/substructure/apis.yml: open an issue on github.com/api-evangelist/substructure 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 →

APIs 1

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

Substructure API

Substructure API as documented publicly: 40 operations. Contract generated from the documentation by API Evangelist (2026-10-19); not the provider's own document.

Substructure API pricing

Prices published by Substructure, read 2026-10-19 from substructure.ai/pricing. A free plan or tier is listed.

Plan	Price
Free tier	Free
Pay-as-you-go	$0.02 a credit

Plan details, limits and sources →

Pricing Plans 1

Published pricing tiers and plan structures.

Substructure Plans Pricing

2 plans

PLANS

Terms of Service 1

What its API terms permit and prohibit, quoted from its own page.

Substructure

8 quoted statements, read from Substructure's own page on 2026-11-10.

TERMS

Privacy & Data 1

Its role, the data it processes, retention and transfers, quoted from its own privacy page.

Substructure

19 quoted statements, read from Substructure's own page on 2026-11-10.

PRIVACY

Eligibility 1

Who may sign up and where, quoted from its own terms.

Substructure

2 quoted statements, read from Substructure's own page on 2026-11-10.

ELIGIBILITY

AI Preferences 1

Its stance on AI training, inference and agents, quoted from its own pages.

Substructure

3 quoted statements, read from Substructure's own page on 2026-11-10.

AI PREFS

Data License 1

How its data and outputs may be reused, quoted from its own terms.

Substructure

1 quoted statement, read from Substructure's own page on 2026-11-10.

LICENSE

Event Specifications 1

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

Substructure Webhooks

ASYNCAPI

Semantic Vocabularies 1

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

Substructure Context

46 classes · 64 properties

JSON-LD

Spectral Rules 1

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

Substructure API Rules

12 rules · 9 error-severity 1 warn-severity 2 info-severity

SPECTRAL

JSON Schema 6

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

GetApiV1ProjectsProjectApiKeysResponse

4 properties

JSON SCHEMA

GetApiV1ProjectsProjectLlmResponse

4 properties

JSON SCHEMA

GetResponse

2 properties

JSON SCHEMA

PostApiChannelsAgUiAgentsAgentidRunRequest

7 properties

JSON SCHEMA

PostApiMachineSessionsSessionidCallsSettleRequest

7 properties

JSON SCHEMA

PostApiMachineSessionsSubmitRequest

7 properties

JSON SCHEMA

Security Posture 2

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

Substructure Authentication

3 schemes

SECURITY

Substructure Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

AIPreferences

AIPreferences

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

Webhooks

DataModel

Conformance

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 6

Pricing, plans, and the legal terms of use

Plans

Pricing

TermsOfService

PrivacyPolicy

UsageTerms

DataLicense

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 4

Properties that don't map to a standard resource type

Hosts

Vendors

DataProcessing

Eligibility

Source (apis.yml)

aid: substructure
name: Substructure
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
  probe_state: unreadable
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-13'
  method: derived
image: https://substructure.ai/og.png?t=subs%2C+the+cloud+native+agent+harness.&v=6
description: Substructure provides a cloud‑native agent harness called subs that enables developers to run unprivileged agents
  locally or as a client‑server system. It offers a hosted deployment, integrates with MCP servers for tool access, and supports
  a variety of LLM back‑ends. The platform includes extensive documentation, pricing details, llms.txt configuration, and
  open‑source tooling on GitHub. Substructure aims to simplify building AI‑driven workflows with secure, sandboxed execution.
url: https://raw.githubusercontent.com/api-evangelist/substructure/refs/heads/main/apis.yml
x-type: company
x-source: harvest:g2-catalog
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-19 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-18'
modified: '2026-10-18'
tags:
- Company
- Artificial Intelligence
- Agents
- Cloud-Native
- Automation
tags_raw:
- Company
- AI
- Agent
- Cloud-native
- Automation
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Plans
  url: plans/substructure-plans-pricing.yml
- type: Spectral
  url: rules/substructure-rules.yml
- type: JSONLD
  url: json-ld/substructure-context.jsonld
- type: Vocabulary
  url: vocabulary/substructure-vocabulary.yml
- type: Webhooks
  url: asyncapi/substructure-webhooks.yml
- type: DataModel
  url: data-model/substructure-data-model.yml
- type: Authentication
  url: authentication/substructure-authentication.yml
- type: Conformance
  url: conformance/substructure-conformance.yml
- type: LLMsTxt
  url: llms/substructure-llms.txt
- type: Hosts
  url: hosts/substructure-hosts.yml
- type: Vendors
  url: vendors/substructure-vendors.yml
- type: DeveloperPortal
  url: https://api.substructure.ai`
- type: DomainSecurity
  url: security/substructure-domain-security.yml
- type: Website
  url: https://substructure.ai/
- type: Documentation
  url: https://substructure.ai/docs
- type: GettingStarted
  url: https://substructure.ai/docs/quick-start
- type: Pricing
  url: https://substructure.ai/pricing
- type: Blog
  url: https://substructure.ai/blog
- type: GitHubOrganization
  url: https://github.com/substructureai
- type: TermsOfService
  url: https://substructure.ai/terms
- type: PrivacyPolicy
  url: https://substructure.ai/privacy
- type: Support
  url: https://app.substructure.ai/login
- type: UsageTerms
  url: terms/substructure-terms-of-service.yml
- type: DataProcessing
  url: privacy/substructure-privacy-policy.yml
- type: Eligibility
  url: eligibility/substructure-eligibility.yml
- type: AIPreferences
  url: ai-preferences/substructure-ai-preferences.yml
- type: DataLicense
  url: data-license/substructure-data-license.yml
apis:
- aid: substructure:substructure-api
  name: Substructure API
  description: 'Substructure API as documented publicly: 40 operations. Contract generated from the documentation by API Evangelist
    (2026-10-19); not the provider''s own document.'
  humanURL: https://substructure.ai/docs/api
  baseURL: https://api.substructure.ai
  properties:
  - type: OpenAPI
    url: openapi/_ae-authored/substructure-openapi-generated.yml
    x-provenance: generated
  - type: JSONSchema
    url: json-schema/substructure-get-response-schema.json
  - type: JSONSchema
    url: json-schema/substructure-post-api-machine-sessions-submit-request-schema.json
  - type: JSONSchema
    url: json-schema/substructure-post-api-machine-sessions-sessionid-calls-settle-request-schema.json
  - type: JSONSchema
    url: json-schema/substructure-get-api-v1-projects-project-api-keys-response-schema.json
  - type: JSONSchema
    url: json-schema/substructure-get-api-v1-projects-project-llm-response-schema.json
  - type: JSONSchema
    url: json-schema/substructure-post-api-channels-ag-ui-agents-agentid-run-request-schema.json
x-coverage:
  state: unreadable
  reason: no-machine-readable-spec
  detail: The API host https://api.substructure.ai returns HTML login page instead of a machine‑readable OpenAPI document.
  evidence:
  - url: https://api.substructure.ai/openapi.json
    status: 200
  checked: '2026-10-19'
x-enrichment:
  date: '2026-10-19'
  status: enriched
  artifacts_added: 25
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Substructure API — frequently asked questions

Does Substructure have an API?

Yes. APIs.io lists 1 API from Substructure, including Substructure API.

Is there an OpenAPI specification for the Substructure API?

Yes. APIs.io indexes 1 OpenAPI specification for Substructure, each linked for download from this page.

How do I authenticate with the Substructure API?

Substructure uses bearer-token authentication (3 schemes). The details are profiled on APIs.io as Substructure Authentication.

How much does the Substructure API cost?

Substructure publishes its prices; its Pay-as-you-go plan is $0.02 a credit as of 2026-10-19. APIs.io lists 2 pricing plans for Substructure, with each plan's price, limits and inclusions under Pricing on this page.

Is the Substructure API ready for AI agents?

Substructure has a Kin Score of 42.3 out of 100 (developing) and an Agent Readiness score of 21.5 (agent-aware), scored by API Evangelist on 2026-11-13.

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