OnPay website screenshot

OnPay

OnPay is an Atlanta, Georgia based provider of full-service online payroll, HR, and employee benefits software for small and mid-size US businesses, founded in 2011 and funded by Carrick Capital Partners. The platform runs payroll and direct deposit, files federal, state, and local payroll taxes, and handles onboarding, PTO, org charts, health insurance, 401(k), and workers' compensation. For developers, OnPay publishes a partner-only REST API (v2) documented on a public ReadMe hub, covering employees, employee deductions, wages, leave, tax fields, bank accounts, terminations and rehires, company worksites, locations, departments and positions, pay schedules, and payroll reporting. Access is limited to approved partners, authorized with OAuth 2.0 authorization-code grants against app.onpay.com and role-scoped bearer tokens.

OnPay publishes 6 APIs on the APIs.io network, including Company API, Deductions API, Employees API, and 3 more. Tagged areas include Payroll, Human Resources, Employee Benefits, payroll-tax, and Small Business.

OnPay’s developer surface includes documentation, API reference, getting-started guide, support, engineering blog, pricing, signup flow, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub
38.0/100 thin ▬ flat Agent 29/100 agent ready saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0
AccessSelf serve
1 APIs
PayrollHuman ResourcesEmployee Benefitspayroll-taxSmall BusinessWorkforce ManagementFintechHR TechTime and Attendanceretirement-401k

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0
Composite quality — 38.0/100 · thin
Contract Quality 9.7 / 23
Developer Ergonomics 7.2 / 18
Access Clarity 9.5 / 18
Operational Transparency 1.2 / 12
Contract Governance 0.5 / 11
Discoverability 6.8 / 9
Create-or-Update Ergonomics 0.0 / 10
Agent readiness — 29/100 · 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 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 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
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.
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/onpay: 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.

OnPay Company API

The Company API from OnPay — 17 operation(s) for company.

OnPay Deductions API

The Deductions API from OnPay — 7 operation(s) for deductions.

OnPay Employees API

The Employees API from OnPay — 14 operation(s) for employees.

OnPay Pay Runs API

The Pay-runs API from OnPay — 2 operation(s) for pay-runs.

OnPay Reports API

The Reports API from OnPay — 2 operation(s) for reports.

OnPay User API

The User API from OnPay — 1 operation(s) for user.

Open Collections 7

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

API Collection

OPEN COLLECTION

OnPay Company API

OPEN COLLECTION

OnPay Deductions API

OPEN COLLECTION

OnPay Employees API

OPEN COLLECTION

OnPay Pay Runs API

OPEN COLLECTION

OnPay Reports API

OPEN COLLECTION

OnPay User API

OPEN COLLECTION

Scroll for all 7

Security Posture 3

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

Onpay Authentication

apiKey/oauth2 · 2 schemes

SECURITY

Onpay Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Onpay Vulnerability Disclosure

Hackerone · contact published

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

Onpay Scopes

6 scopes · authorizationCode

6 scopes

SCOPES

Agentic Access 1

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

Onpay Agentic Access

58 operations · 28 acting

58 operations · 28 acting

AGENTIC

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 SignUp
SignUp
 Login
Login

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

X-MCPServerCandidate
X-MCPServerCandidate
 AgenticAccess
AgenticAccess
 LLMsTxt
LLMsTxt
 AgentSkill
AgentSkill

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 Conformance
Conformance
 DataModel
DataModel

Access & Security 6

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity
 Security
Security
 Compliance
Compliance
 Authentication
Authentication
 OAuthScopes
OAuthScopes
 VulnerabilityDisclosure
VulnerabilityDisclosure

Operate 1

Status, limits, changes, and where to get help

Support
Support

Commercial 3

Pricing, plans, and the legal terms of use

Pricing
Pricing
 TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy

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)

apis.yml Raw ↑ 
aid: onpay
name: OnPay
description: OnPay is an Atlanta, Georgia based provider of full-service online payroll, HR, and employee benefits software
  for small and mid-size US businesses, founded in 2011 and funded by Carrick Capital Partners. The platform runs payroll
  and direct deposit, files federal, state, and local payroll taxes, and handles onboarding, PTO, org charts, health insurance,
  401(k), and workers' compensation. For developers, OnPay publishes a partner-only REST API (v2) documented on a public ReadMe
  hub, covering employees, employee deductions, wages, leave, tax fields, bank accounts, terminations and rehires, company
  worksites, locations, departments and positions, pay schedules, and payroll reporting. Access is limited to approved partners,
  authorized with OAuth 2.0 authorization-code grants against app.onpay.com and role-scoped bearer tokens.
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
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  - scopes
  - security
  - sandbox
  generated: '2026-09-02'
  method: derived
image: https://onpay.com/wp-content/uploads/2017/08/d9fo84j1zi.jpg
url: https://raw.githubusercontent.com/api-evangelist/onpay/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
specificationVersion: '0.23'
created: '2026-08-04'
modified: '2026-08-04'
tags:
- Payroll
- Human Resources
- Employee Benefits
- payroll-tax
- Small Business
- Workforce Management
- Fintech
- HR Tech
- Time and Attendance
- retirement-401k
tags_raw:
- payroll
- human-resources
- employee-benefits
- payroll-tax
- small-business
- workforce-management
- fintech
- hr-tech
- time-and-attendance
- retirement-401k
apis:
- aid: onpay:onpay-company-api
  name: OnPay Company API
  description: The Company API from OnPay — 17 operation(s) for company.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - Company
  properties:
  - type: OpenAPI
    url: openapi/onpay-company-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
- aid: onpay:onpay-deductions-api
  name: OnPay Deductions API
  description: The Deductions API from OnPay — 7 operation(s) for deductions.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - Deductions
  properties:
  - type: OpenAPI
    url: openapi/onpay-deductions-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
- aid: onpay:onpay-employees-api
  name: OnPay Employees API
  description: The Employees API from OnPay — 14 operation(s) for employees.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - Employees
  properties:
  - type: OpenAPI
    url: openapi/onpay-employees-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
- aid: onpay:onpay-pay-runs-api
  name: OnPay Pay Runs API
  description: The Pay-runs API from OnPay — 2 operation(s) for pay-runs.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - Pay Runs
  tags_raw:
  - Pay-runs
  properties:
  - type: OpenAPI
    url: openapi/onpay-pay-runs-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
- aid: onpay:onpay-reports-api
  name: OnPay Reports API
  description: The Reports API from OnPay — 2 operation(s) for reports.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - Reports
  properties:
  - type: OpenAPI
    url: openapi/onpay-reports-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
- aid: onpay:onpay-user-api
  name: OnPay User API
  description: The User API from OnPay — 1 operation(s) for user.
  humanURL: https://onpay.readme.io/reference/authorization
  baseURL: https://api.onpay.com/v2
  tags:
  - User
  properties:
  - type: OpenAPI
    url: openapi/onpay-user-api-openapi.yml
  - type: Documentation
    url: https://onpay.readme.io/
  - type: APIReference
    url: https://onpay.readme.io/reference/authorization
  - type: Authentication
    url: authentication/onpay-authentication.yml
  - type: OAuthScopes
    url: scopes/onpay-scopes.yml
  - type: ErrorCatalog
    url: errors/onpay-problem-types.yml
  - type: Conventions
    url: conventions/onpay-conventions.yml
  - type: DataModel
    url: data-model/onpay-data-model.yml
  - type: LLMsTxt
    url: https://onpay.readme.io/llms.txt
common:
- type: X-MCPServerCandidate
  url: mcp/onpay-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: Overlay
  url: overlays/onpay-api-overlay.yaml
- type: DomainSecurity
  url: security/onpay-domain-security.yml
- type: AgenticAccess
  url: agentic-access/onpay-agentic-access.yml
- type: Website
  url: https://onpay.com/
- type: DeveloperPortal
  url: https://onpay.readme.io/
- type: Documentation
  url: https://onpay.readme.io/
- type: APIReference
  url: https://onpay.readme.io/reference/authorization
- type: GettingStarted
  url: https://onpay.readme.io/docs/getting-started
- type: Support
  url: https://help.onpay.com/hc/en-us
- type: Blog
  url: https://onpay.com/insights/
- type: Pricing
  url: https://onpay.com/payroll/software/costs-pricing/
- type: SignUp
  url: https://onpay.com/get-started/
- type: Login
  url: https://app.onpay.com/app/login
- type: TermsOfService
  url: https://onpay.com/terms-of-service/
- type: PrivacyPolicy
  url: https://onpay.com/privacy/
- type: Security
  url: https://onpay.com/security/
- type: Compliance
  url: https://onpay.com/security/
- type: Integrations
  url: https://onpay.com/app-directory/
- type: LLMsTxt
  url: llms/onpay-llms.txt
- type: Authentication
  url: authentication/onpay-authentication.yml
- type: OAuthScopes
  url: scopes/onpay-scopes.yml
- type: Conventions
  url: conventions/onpay-conventions.yml
- type: ErrorCatalog
  url: errors/onpay-problem-types.yml
- type: Lifecycle
  url: lifecycle/onpay-lifecycle.yml
- type: Conformance
  url: conformance/onpay-conformance.yml
- type: DataModel
  url: data-model/onpay-data-model.yml
- type: VulnerabilityDisclosure
  url: security/onpay-vulnerability-disclosure.yml
- type: AgentSkill
  url: skills/_index.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-08-04'
  status: enriched
  artifacts_added: 20
  pass: local-v1

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this
  • find_providersBrowse and filter every provider in the catalog.
  • get_provider_artifactsEvery artifact this provider publishes, grouped by type.
  • get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
  • get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
  • get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
  • get_provider_ratingPRO — composite, band, trend and facet scores.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This provider 
curl "https://apis.io/api/v1/providers/onpay"
All providers 
curl "https://apis.io/api/v1/providers?limit=25"
Every operation they expose 
curl "https://apis.io/api/v1/providers/onpay/operations?limit=25"
How their score was established 
curl "https://apis.io/api/v1/providers/onpay/evidence"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.