FreeAgent

FreeAgent is UK-focused cloud accounting software for small businesses, freelancers, and accountants, providing invoicing, expense tracking, time tracking, project management, banking, payroll, and Self Assessment / VAT filing through HMRC's Making Tax Digital. The FreeAgent API is a RESTful service that exposes contacts, invoices, estimates, expenses, bills, timeslips, projects, bank accounts, bank transactions, transaction explanations, and tax timeline events for company accounts and accountancy practices. Authentication uses OAuth 2.0 (authorization code flow) and responses are available in JSON or XML.

FreeAgent publishes 4 API contracts indexed on the APIs.io network, including REST API, Contacts API, Invoices API, and 1 more. Tagged areas include Accounting, Small Business, Invoicing, Bookkeeping, and Expenses.

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

FreeAgent’s developer surface includes authentication, documentation, pricing, signup flow, support, engineering blog, and 9 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

39.7/100 developing ▬ flat Agent 26/100 agent aware Front door AI 3/6 light Heartbeat 100/100 alive saas Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessSelf serve

1 published contract

Accounting Small Business Invoicing Bookkeeping Expenses Payroll VATHMRCMaking Tax Digital

What this lets a business do 1

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

Financial Management

BC-200

Invoices

GET /invoices POST /invoices GET /invoices/{id} GET /invoices/{id}/pdf

Kin Score

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

Composite quality — 39.7/100 · developing

Contract Quality 8.7 / 19

Developer Ergonomics 9.3 / 15

Access Clarity 2.9 / 15

Operational Transparency 2.3 / 10

Contract Governance 1.2 / 9

Discoverability 5.0 / 8

Regulatory Posture 4.1 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 26/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 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 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 6 / 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 Employment & Payroll 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 →
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 →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →

8 more unmet checks in the Agent Readiness table above.

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

Access Clarity scores 19.1 — up to +16.2 composite points Ask about this →
Contract Quality scores 46.3 — up to +13.4 composite points Ask about this →
Contract Governance scores 13.6 — up to +10.4 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/freeagent/apis.yml: open an issue on github.com/api-evangelist/freeagent 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
Amazon Seller Ecosystem (Selling Partner Appstore, Amazon Ads partners)	mixed	26.8	-	-
Raycast Store Extensions (first-party publishers + community-wrapped products)	mixed	26.8	-	-

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 3

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)

Postman Collections

measured — observed by APIs.io (published)

OAuth 2.0

measured — observed by APIs.io (declared)

APIs 4

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

FreeAgent REST API

RESTful API for the FreeAgent cloud accounting platform. Provides full access to invoices, estimates, contacts, bills, expenses, projects, timeslips, bank accounts, transactions...

FreeAgent Contacts API

The Contacts API from FreeAgent — 2 operation(s) for contacts.

FreeAgent Invoices API

The Invoices API from FreeAgent — 10 operation(s) for invoices.

FreeAgent Bank Accounts API

The Bank Accounts API from FreeAgent — 2 operation(s) for bank accounts.

Open Collections 4

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

FreeAgent BankAccounts API

OPEN COLLECTION

FreeAgent BankAccounts Contacts API

OPEN COLLECTION

FreeAgent BankAccounts Invoices API

OPEN COLLECTION

FreeAgent API

OPEN COLLECTION

Spectral Rules 1

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

FreeAgent API Rules

50 rules · 48 error-severity 1 warn-severity 1 info-severity

SPECTRAL

Security Posture 3

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

FreeAgent Authentication

oauth2 · 1 scheme

SECURITY

FreeAgent Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

FreeAgent Vulnerability Disclosure

security.txt · contact published

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

FreeAgent Scopes

OAuth 2.0 · no documented scopes

0 scopes

SCOPES

Agentic Access (API Evangelist recommendations) 1

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

FreeAgent Agentic Access

23 operations · 15 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

Signup

Signup

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Access & Security 4

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Authentication

Authentication

OAuthScopes

OAuthScopes

Operate 2

Status, limits, changes, and where to get help

Support

Support

StatusPage

StatusPage

Commercial 1

Pricing, plans, and the legal terms of use

Pricing

Pricing

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

aid: freeagent
name: FreeAgent
description: FreeAgent is UK-focused cloud accounting software for small businesses, freelancers, and accountants, providing
  invoicing, expense tracking, time tracking, project management, banking, payroll, and Self Assessment / VAT filing through
  HMRC's Making Tax Digital. The FreeAgent API is a RESTful service that exposes contacts, invoices, estimates, expenses,
  bills, timeslips, projects, bank accounts, bank transactions, transaction explanations, and tax timeline events for company
  accounts and accountancy practices. Authentication uses OAuth 2.0 (authorization code flow) and responses are available
  in JSON or XML.
type: Index
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: self-serve
  trial: false
  try_now: false
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Self-serve signup
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-11-13'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/freeagent.png
tags:
- Accounting
- Small Business
- Invoicing
- Bookkeeping
- Expenses
- Payroll
- VAT
- HMRC
- Making Tax Digital
url: https://raw.githubusercontent.com/api-evangelist/freeagent/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-05-11'
specificationVersion: '0.23'
apis:
- aid: freeagent:rest-api
  name: FreeAgent REST API
  description: RESTful API for the FreeAgent cloud accounting platform. Provides full access to invoices, estimates, contacts,
    bills, expenses, projects, timeslips, bank accounts, transactions, and accountancy-practice resources. Authentication
    is OAuth 2.0 authorization code flow; a sandbox is available at api.sandbox.freeagent.com.
  humanURL: https://dev.freeagent.com/docs
  baseURL: https://api.freeagent.com/v2
  tags:
  - Accounting
  - Invoicing
  - Bookkeeping
  - Expenses
  - Bank Feeds
  - OAuth
  - Authentication
  tags_raw:
  - Accounting
  - Invoicing
  - Bookkeeping
  - Expenses
  - Bank Feeds
  - OAuth 2.0
  - Authentication
  properties:
  - type: Documentation
    url: https://dev.freeagent.com/docs
  - type: Authentication
    url: https://dev.freeagent.com/docs/oauth
  - type: GettingStarted
    url: https://dev.freeagent.com/docs/quick_start
  - type: Sandbox
    url: https://api.sandbox.freeagent.com
  - type: PostmanCollection
    url: https://github.com/fac/postman-freeagent-api-collection
- aid: freeagent:freeagent-contacts-api
  name: FreeAgent Contacts API
  description: The Contacts API from FreeAgent — 2 operation(s) for contacts.
  humanURL: https://dev.freeagent.com/docs
  baseURL: https://api.freeagent.com/v2
  tags:
  - Contacts
  properties:
  - type: OpenAPI
    url: openapi/freeagent-contacts-api-openapi.yml
- aid: freeagent:freeagent-invoices-api
  name: FreeAgent Invoices API
  description: The Invoices API from FreeAgent — 10 operation(s) for invoices.
  humanURL: https://dev.freeagent.com/docs
  baseURL: https://api.freeagent.com/v2
  tags:
  - Invoices
  properties:
  - type: OpenAPI
    url: openapi/freeagent-invoices-api-openapi.yml
- aid: freeagent:freeagent-bank-accounts-api
  name: FreeAgent Bank Accounts API
  description: The Bank Accounts API from FreeAgent — 2 operation(s) for bank accounts.
  humanURL: https://dev.freeagent.com/docs
  baseURL: https://api.freeagent.com/v2
  tags:
  - Bank Accounts
  properties:
  - type: OpenAPI
    url: openapi/freeagent-bank-accounts-api-openapi.yml
common:
- type: CapabilityMap
  url: capabilities/freeagent-capability-edges.yml
  name: FreeAgent Business Capability Map
- type: AgenticAccess
  url: agentic-access/freeagent-agentic-access.yml
- type: VulnerabilityDisclosure
  url: security/freeagent-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/freeagent-domain-security.yml
- type: Authentication
  url: authentication/freeagent-authentication.yml
- type: OAuthScopes
  url: scopes/freeagent-scopes.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/freeagent
- type: Website
  url: https://www.freeagent.com
- type: Documentation
  url: https://dev.freeagent.com/docs
- type: DeveloperPortal
  url: https://dev.freeagent.com
- type: Pricing
  url: https://www.freeagent.com/pricing/
- type: Signup
  url: https://signup.freeagent.com/
- type: Support
  url: https://support.freeagent.com
- type: StatusPage
  url: https://status.freeagent.com
- url: https://www.freeagent.com/feed.rss
  type: Blog
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

FreeAgent API — frequently asked questions

Does FreeAgent have an API?

Yes. APIs.io lists 4 APIs from FreeAgent, including FreeAgent REST API, FreeAgent Contacts API and FreeAgent Invoices API, and 1 more.

Is there an OpenAPI specification for the FreeAgent API?

Yes. APIs.io indexes 3 OpenAPI specifications for FreeAgent, each linked for download from this page.

How do I authenticate with the FreeAgent API?

FreeAgent documents its authentication (oauth2 · 1 scheme). The details are profiled on APIs.io as FreeAgent Authentication.

Is the FreeAgent API ready for AI agents?

FreeAgent has a Kin Score of 39.7 out of 100 (developing) and an Agent Readiness score of 25.6 (agent-aware), scored by API Evangelist on 2026-11-13.

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