Need help with your APIs? I offer API discovery, governance & evangelism services. Explore services →
API Evangelist API Evangelist
Discovery
Learnings
Guidance
Toolbox
Alignment
API Evangelist LLC
BILL website screenshot

BILL

BILL (formerly Bill.com) is a cloud-based financial operations platform for small and midsize businesses that automates accounts payable, accounts receivable, and spend & expense management. The BILL API Platform exposes these workflows through the BILL v3 REST API and embeddable BILL Elements UI components, enabling partners and ERPs to integrate bill capture, approvals, payments, and real-time event notifications via webhooks. The API uses session-based authentication with API keys and developer keys against production and sandbox gateways.

agent ready

Limited machine-readable signal and partial portal coverage — documentation a human can read, but little a machine or agent can consume without scraping.

Kin Score

API Evangelist profiles BILL the way a machine reads it — 17 machine-readable artifacts across 11 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.

Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — BILL scores 39.1/100 (thin), with a separate agent-readiness read of 47/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.

Kin Score

This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 39.1/100 · thin
Contract Quality 15.5 / 25
Developer Ergonomics 7.8 / 20
Commercial Clarity 2.1 / 20
Operational Transparency 0.0 / 13
Governance 7.3 / 12
Discoverability 8.8 / 10
Regulatory · Payments 3.9 / 15
Agent readiness — 47/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 15 / 15
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

How we profile BILL

Each block below is one kind of artifact we hold for BILL. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.

APIs 11

Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.

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

BILL v3 API

REST API providing full-breadth access to BILL's Accounts Payable, Accounts Receivable, and Spend & Expense capabilities including bills, invoices, vendors, customers, payments,...

BILL Elements

Low-code, embeddable UI components that surface the BILL Accounts Payable workflow inside partner applications with minimal development effort.

BILL Authentication API

The Authentication API from BILL — 5 operation(s) for authentication.

BILL Bills API

The Bills API from BILL — 4 operation(s) for bills.

BILL Customers API

The Customers API from BILL — 3 operation(s) for customers.

BILL Funding Accounts API

The Funding Accounts API from BILL — 2 operation(s) for funding accounts.

BILL Invoices API

The Invoices API from BILL — 3 operation(s) for invoices.

BILL Organizations API

The Organizations API from BILL — 2 operation(s) for organizations.

BILL Payments API

The Payments API from BILL — 5 operation(s) for payments.

BILL Vendors API

The Vendors API from BILL — 3 operation(s) for vendors.

BILL Webhooks API

The Webhooks API from BILL — 2 operation(s) for webhooks.

Scroll within the panel for all 11 ·

Open Collections 1

Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.

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

BILL v3 API

OPEN COLLECTION

Event Specifications 1

Not every API is request/response. AsyncAPI describes the event-driven and streaming side — the webhooks and channels — so the asynchronous half of the interface is documented the same way the synchronous half is.

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

BILL Webhooks

Outbound webhook event notifications delivered by the BILL v3 API Platform to subscriber `notificationUrl` endpoints. Subscribers register through the BILL v3 webhook subscripti...

ASYNCAPI

Spectral Rules 1

Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.

BILL API Rules

8 rules · 1 errors · 6 warnings

SPECTRAL

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.

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

Bill Authentication

apiKey · 1 scheme

SECURITY

Bill Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.

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

Bill Agentic Access

40 operations · 26 acting

40 operations · 26 acting

AGENTIC

Resources

Every other property we hold for BILL — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.

Get Started 2

Portal, sign-up, and the first successful call

Documentation 2

Reference material describing how the API behaves

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

Access & Security 2

Authentication, authorization, and security posture

Operate 1

Status, limits, changes, and where to get help

Commercial 1

Pricing, plans, and the legal terms of use

Company 2

The organization behind the API

← All providers · Data indexed from github.com/api-evangelist/bill · machine-readable index on apis.io