Affirm API

Name: Affirm API
Brand: Affirm API
Availability: InStock

★ Only Publicly Available OpenAPI DocumentPaymentsPayment Processingbasic23 EndpointsREST

For Agents

Run Affirm buy-now-pay-later checkout, capture and refund transactions, and respond to disputes across 23 REST endpoints.

Install Jentic One Beta

Connect the Affirm API to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Affirm API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.

Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.

Step 1: Jentic One Host machine

# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh

Step 2: Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register       # connects your agent to your Jentic One instance

Jentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.

Capabilities

What an agent can do with Affirm API.

Create and update checkouts to offer Affirm BNPL at the point of sale

Authorize, capture, refund, and void transactions on Affirm financing

List and read transactions and transaction events for reconciliation

GET STARTED

Start building with Affirm API

Explore with Jentic

View OpenAPI Document

Jentic publishes the only available OpenAPI specification for Affirm API, keeping it validated and agent-ready. Affirm is a buy-now-pay-later (BNPL) platform that lets merchants offer instalment financing at checkout. Its v1 API exposes 23 endpoints covering checkouts (store, direct, update, resend), card-based virtual card flows, transactions (authorize, capture, refund, void), settlement events, dispute lifecycle including evidence upload, and supporting file storage. Authentication uses HTTP basic auth with the public_api_key as the username and the private_api_key as the password.

Use Cases

Patterns agents use Affirm API for, with concrete tasks.

★ Buy-Now-Pay-Later Checkout Integration

Add Affirm financing as a payment method at checkout. POST /checkout/store creates a hosted checkout the customer completes on Affirm, POST /checkout/direct supports a direct flow, /checkout/{checkout_id}/update modifies the cart before the customer confirms, and /checkout/resend re-sends the checkout link. Once the customer authorises, POST /transactions creates the transaction record on the merchant side.

Call POST /checkout/store with cart total $499, currency USD, and items array, then return the checkout URL for the customer

Transaction Lifecycle and Reconciliation

Manage the post-authorisation transaction lifecycle. POST /transactions/{transaction_id}/capture moves an authorisation to a captured charge, /void cancels an authorisation that won't be captured, and /refund issues a partial or full refund. GET /transactions/events streams every state change and GET /settlements/events lets finance reconcile Affirm payouts to merchant transactions.

Call POST /transactions/{transaction_id}/capture with the captured amount, then GET /settlements/events to find when the funds settle

Dispute Handling and Evidence Submission

Respond to chargebacks and disputes through the API. GET /disputes lists open disputes, /disputes/{dispute_id} returns the detail, /disputes/{dispute_id}/evidence accepts evidence files (uploaded first via POST /files), and /disputes/{dispute_id}/close closes the dispute. Useful for ops teams who manage many disputes per week and want to push the workflow into a queue tool.

Call POST /files with the evidence document, then POST /disputes/{dispute_id}/evidence with the returned file id and a written response

AI Agent Affirm Operations

Let an AI agent answer 'has this Affirm transaction settled?' or 'refund this order' inside an internal Slack or admin tool. Through Jentic, the agent searches by intent, loads the matching Affirm schema, and executes with the basic-auth keys isolated in the vault. Useful for support and finance teams that want self-service access without building a bespoke admin panel.

Search Jentic for 'refund an affirm transaction', load /transactions/{transaction_id}/refund schema, and execute with the transaction id and refund amount

Key Endpoints

23 endpoints — jentic publishes the only available openapi specification for affirm api, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/checkout/store

Create a hosted Affirm checkout

POST

/checkout/direct

Create a direct Affirm checkout

POST

/transactions

Create a transaction from an authorised checkout

POST

/transactions/{transaction_id}/capture

Capture an authorised transaction

POST

/transactions/{transaction_id}/refund

Refund a captured transaction

POST

/transactions/{transaction_id}/void

Void an unauthorised or pre-capture transaction

GET

/disputes

List open disputes

POST

/disputes/{dispute_id}/evidence

Submit evidence for a dispute

POST

/checkout/store

Create a hosted Affirm checkout

POST

/checkout/direct

Create a direct Affirm checkout

POST

/transactions

Create a transaction from an authorised checkout

POST

/transactions/{transaction_id}/capture

Capture an authorised transaction

POST

/transactions/{transaction_id}/refund

Refund a captured transaction

Why Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

Your Affirm public and private API keys are stored once, encrypted, by your own Jentic One instance as basic-auth credentials and injected at execution time. They never enter the agent's prompt, logs, or context.

Intent-based discovery

Agents search Jentic by intent such as 'refund an Affirm transaction', and Jentic returns the matching v1 operation with its path and body schema so the agent picks refund over void without browsing the reference docs.

Time to first call

FAQs

Specific to using Affirm API through Jentic.

Why is there no official OpenAPI spec for the Affirm API?

Affirm publishes developer documentation but does not distribute a downloadable OpenAPI 3 specification. Jentic generates and maintains this spec so that AI agents and developers can call Affirm API via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.

What authentication does the Affirm API use?

Affirm uses HTTP basic authentication with the public_api_key as the username and the private_api_key as the password, base64-encoded in the Authorization header. Through Jentic the key pair is stored in the vault and applied at execution time.

Does Affirm have a sandbox environment?

Yes. The spec lists two servers - production at https://api.affirm.com/api/v1 and sandbox at https://sandbox.affirm.com/api/v1. Use the sandbox base URL with sandbox keys for integration testing before going live.

How do I capture and refund an Affirm transaction?

After the customer completes a checkout, POST /transactions creates the transaction; POST /transactions/{transaction_id}/capture captures the authorised amount, /refund issues a refund, and /void cancels an authorisation that has not been captured. Each action returns the updated transaction state.

What are the rate limits for the Affirm API?

Affirm applies merchant-tier rate limits but does not declare specific numbers in the spec. HTTP 429 responses indicate the limit has been reached; Jentic surfaces them verbatim so agents can implement back-off.

How do I create a checkout through Jentic?

Run pip install jentic, search Jentic with 'create an affirm checkout for a cart', load the /checkout/store schema, and execute with the cart total, currency, items, and merchant URLs. Jentic injects the basic-auth keys at execution time.

Can I limit what my agent is allowed to do with the Affirm API?

Yes. Because you run Jentic One yourself, your own rules decide which Affirm operations and credentials the agent may use. You can allow only specific operations, such as POST /transactions/{transaction_id}/capture, while withholding destructive ones like /refund and /void unless you explicitly add them. Since Affirm puts the transaction id in the URL path, a rule can also pin the agent to actions on a single transaction rather than the whole account.

Affirm API

Connect the Affirm API to your agent

Capabilities

Start building with Affirm API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs