How AI is applied across API Evangelist and APIs.io. Read my AI disclosure →
API Evangelist API Evangelist
Discovery
Learnings
Guidance
Toolbox
Alignment
API Evangelist LLC
Discovery
Learnings
Guidance
Toolbox
Alignment
API Evangelist LLC

Need help?

Contact us
Affirm

Affirm Transactions API

Post-authorization transaction management operations including capture, void, and refund.

Documentation Provider Profile APIs.io OpenAPI GitHub

Affirm Transactions API is one of 11 APIs that Affirm publishes on the APIs.io network, described by a machine-readable OpenAPI specification.

Tagged areas include Transaction. The published artifact set on APIs.io includes an OpenAPI specification.

This API exposes 7 operations across 5 paths, and defines 5 schemas. It is described by OpenAPI 3.2.0, at version 1.0.

Requests are made against 2 base URLs: https://api.affirm.com/api/v1, https://sandbox.affirm.com/api/v1.

7 operations 5 paths 5 schemas 2 GET5 POST

Metadata

The identity and technical contract details declared by the specification.

Specification
OpenAPI 3.2.0
API Version
1.0
Base URL
https://api.affirm.com
Authentication
HTTP Basic
Contact
Affirm Developer Support
Terms of Service
View terms
Resource Areas
1

Authentication & Security 1

Affirm Transactions API declares 1 security scheme for authenticating requests. It accepts HTTP basic authentication (basicAuth). By default, every request must be authenticated.

  • basicAuth — HTTP Basic Authentication using the merchant's public API key as the username and private API key as the password, Base64-encoded as per RFC 7617.

Paths & Operations 7

Across 5 paths, the API surfaces 7 operations — 2 GET, 5 POST. Each is listed below with its method, path, parameters, and response codes.

Transactions 7

Post-authorization transaction management operations including capture, void, and refund.

POST
/transactions/{id}/capture
Affirm Capture a Transaction
captureDirectTransaction 1 param body → 200400401404
POST
/transactions/{id}/void
Affirm Void a Transaction
voidDirectTransaction 1 param → 200400401404
POST
/transactions/{id}/refund
Affirm Refund a Transaction
refundDirectTransaction 1 param body → 200400401404
GET
/transactions
Affirm List Transactions
listTransactions 2 params → 200401
POST
/transactions
Affirm Authorize a Transaction
authorizeTransaction body → 200400401
GET
/transactions/{id}
Affirm Read a Transaction
readTransaction 1 param → 200401404
POST
/transactions/{id}
Affirm Update a Transaction
updateTransaction 1 param body → 200400401404

Schemas 5

The contract defines 5 schemas that model the data the API accepts and returns. The most detailed are Transaction_2 (13 properties), Transaction (9 properties), TransactionEvent (8 properties), Error_2 (4 properties). Each schema is shown below with its type and property counts.

Error
object
Standard error response returned by the Affirm API.
3 properties
Transaction
object
Represents an Affirm payment transaction at any point in its lifecycle.
9 properties
Error_2
object
Standard error response returned by the Affirm API.
4 properties
Transaction_2
object
Represents an Affirm payment transaction, capturing the full lifecycle from authorization through capture, refund, and void operations.
13 properties
TransactionEvent
object
Represents a single event in the lifecycle of a transaction, such as an authorization, capture, refund, or void.
8 properties

Specification

The full machine-readable OpenAPI contract behind this narrative.

Source

affirm-transactions-api-openapi.yml Raw ↑

Other APIs Affirm publishes across the network.

Affirm Checkout API
AE Profile APIs.io
Affirm Charges API
AE Profile APIs.io
Affirm Authorization API
AE Profile APIs.io
Affirm Cards API
AE Profile APIs.io
Affirm Checkouts API
AE Profile APIs.io
Affirm Disputes API
AE Profile APIs.io
Affirm Promos API
AE Profile APIs.io
Affirm Settlement Events API
AE Profile APIs.io
Affirm Transaction Events API
AE Profile APIs.io
#Transaction
← Back to A APIs
API Details
ID
affirm:affirm-transactions-api
Base URL
https://api.affirm.com
Docs
https://docs.affirm.com/developers
Provider
Affirm
APIs.io →  GitHub →
Explore more
All APIs Providers APIs.io Network
Work with this as data

Every API here is available over the API and to AI agents over MCP. APIs is not yet its own endpoint on the v1 API. Reach this content through network search and the tag graph, or the MCP server below.

Installs https://mcp.apievangelist.com/mcp in Claude, Cursor, VS Code and the rest — one button, every client.

MCP tools for apis
4 tools reach this content
  • search_api_evangelistSearch every content type across the network at once.
  • find_relatedThe shared-tag relevance graph — what else covers this.
  • get_tagEverything one tag labels, across all content types.
  • guide_topicPRO — a curated bundle for a topic: area, guidance, rules, papers, stories, services.
All tools & prompts
Call it yourself
curl for this page
Search the network for this 
curl "https://api.apievangelist.com/v1/search?q=affirm-transactions-api&limit=10"
Everything under a tag 
curl "https://api.apievangelist.com/v1/tags/affirm-transactions-api"

Discovery needs no key. Full bodies and the synthesis endpoints are Pro.

Get an API key

Free tier, no email required. Sign in with whichever identity you already have.

GitHub Google LinkedIn

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

Where this information came from

This is an independent, third-party profile of Affirm Transactions API, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.

The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.

Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.

info@apievangelist.com · Read the full data-sourcing policy →
On a security or compliance team? Put security in the subject line and you will get a person, not a form — we will tell you exactly which public URLs this profile was built from.