SDKs

The InFlow SDKs implement InFlow Payments (MPP and x402) for sellers and buyers in four languages. Each SDK also has a seller module for Visa Trusted Agent Protocol (TAP) verification.

Language	Repository	Package	Runtime	Latest version
Node.js and TypeScript	`inflowpayai/inflow-node`	`@inflowpayai/*` on npm	Node 22 or later	See the packages
Python	`inflowpayai/inflow-python`	`inflowpay` on PyPI	Python 3.11 or later
Go	`inflowpayai/inflow-go`	`github.com/inflowpayai/inflow-go`	Go 1.26 or later
Rust	`inflowpayai/inflow-rust`	`inflow-*` crates on crates.io	Rust 1.93 or later

All four SDKs are before version 1.0. A minor version can contain incompatible API changes. A patch version contains only compatible fixes. InFlow supports the latest stable release of each SDK. For Enrollment (AEP) and Discovery (ODP), use the SDKs from the foundations of those protocols. See AEP and ODP SDKs.

Environments

Each SDK takes an environment value. The default is production.

Environment	API host
Sandbox	`https://sandbox.inflowpay.ai`
Production	`https://api.inflowpay.ai`

The environment must match the dashboard that issued the API key. Every SDK reads the key from INFLOW_API_KEY in its examples. MPP sellers also need MPP_SECRET_KEY.

Node.js and TypeScript

Package	Role	What it contains
`@inflowpayai/x402`	Shared	Core types and an HTTP client for x402.
`@inflowpayai/x402-seller`	Seller	A facilitator client and a seller client.
`@inflowpayai/x402-buyer`	Buyer	A subclass of the foundation `x402Client` for buyers.
`@inflowpayai/mpp`	Shared	MPP definitions, wire types, a codec, and an HTTP client.
`@inflowpayai/mpp-seller`	Seller	The InFlow, Tempo, Stripe, and Visa CARD seller methods for `mppx`, InFlow subscriptions, and more than one charge on one endpoint.
`@inflowpayai/mpp-buyer`	Buyer	The InFlow buyer method for `mppx`, with a buyer endpoint driver.
`@inflowpayai/tap-seller`	Seller	Local verification of trusted-agent request signatures.

Use case	Command
x402 seller on Express	`pnpm add @inflowpayai/x402-seller @x402/express @x402/core @x402/extensions express`
x402 seller on Fastify	`pnpm add @inflowpayai/x402-seller @x402/fastify @x402/core @x402/extensions fastify`
x402 seller on Next 16 App Router	`pnpm add @inflowpayai/x402-seller @x402/next @x402/core @x402/extensions next`
x402 buyer	`pnpm add @inflowpayai/x402-buyer @x402/core`
MPP seller	`pnpm add @inflowpayai/mpp-seller mppx@^0.8.17`
MPP buyer	`pnpm add @inflowpayai/mpp-buyer mppx@^0.8.17`

The packages declare engines.node: >=22.0.0.

Python

The distribution and the import namespace are both inflowpay. Extras select the protocols and the framework.

Extra	What it adds
`mpp`	The MPP payment library.
`x402`	The x402 payment library.
`evm`, `svm`	The x402 external-wallet dependencies.
`mcp`	The MCP dependencies for both protocols.
`fastapi`	The optional FastAPI integration.
`tap`	TAP seller verification.

Use case	Command
MPP seller	`pip install 'inflowpay[mpp,fastapi]' uvicorn`
x402 seller	`pip install 'inflowpay[x402,fastapi]' uvicorn`
MPP buyer	`pip install 'inflowpay[mpp]'`
x402 buyer	`pip install 'inflowpay[x402]'`
TAP seller	`pip install 'inflowpay[tap,fastapi]' uvicorn`

The clients do not depend on FastAPI. They also work with other asynchronous frameworks. The HTTP client is httpx.

Go

go get github.com/inflowpayai/inflow-go@v0.3.1

Package	Role
`mpp/seller`	MPP seller. `Protect` returns a standard `http.Handler`.
`mpp/buyer`	MPP buyer.
`x402/seller`	x402 seller, with the upstream `nethttp` middleware.
`x402/buyer`	x402 buyer. `x402/buyer/eip7702` adds EIP-7702 support.
`tap/seller`	TAP seller verification.

The Go SDK works with net/http. Set Environment: inflow.Sandbox for tests.

Rust

Crate	What it contains
`inflow-core`	Shared code for the other crates.
`inflow-mpp`	Shared MPP code.
`inflow-mpp-seller`	Signed offers, validation, and settlement for InFlow, Tempo, Stripe, and Visa CARD charges.
`inflow-mpp-buyer`	An explicit credential workflow for MPP challenges.
`inflow-x402`	Shared x402 code.
`inflow-x402-seller`	x402 seller.
`inflow-x402-buyer`	x402 buyer.
`inflow-x402-axum`	Optional Axum and Tower protected endpoints that use the upstream x402 middleware.
`inflow-tap-seller`	TAP seller verification.

Add the crates to Cargo.toml.

[dependencies]
inflow-mpp-seller = "0.4.0"

For an MPP seller, add inflow-mpp-seller, inflow-mpp, and serde_json. The MPP seller handler runs inside any HTTP framework that uses the Tokio runtime of your application.

Feature differences

Check this table before you choose a language.

Feature	Node.js	Python	Go	Rust
MPP seller subscriptions	Yes	No	Yes	No
More than one InFlow offer on one endpoint	Yes	No	Yes	Not stated
MPP over MCP	Yes, for buyers	Yes, for buyers	No	Yes, with your own MCP client
Stripe and Visa CARD seller methods	Yes	Yes	Yes	Yes
Framework integration	Express, Fastify, Hono, Next.js	FastAPI	`net/http`	Axum and Tower, for x402

Stripe acceptance is for sellers only. The InFlow buyer SDKs do not create Stripe tokens. The Rust x402 Axum layer rejects automatic upto endpoints, because the upstream middleware settles the full authorized amount.

Examples

Each repository has runnable sandbox examples in its examples folder.

Language	Examples
Node.js	`x402-seller-express`, `x402-seller-hono`, `x402-seller-fastify`, `x402-seller-next`, `x402-buyer-fetch`, `x402-buyer-axios`, `x402-buyer-x402-evm`, `x402-buyer-x402-svm`, `x402-facilitator`, `mpp-aep-seller-express`, `mpp-card-seller-express`, `mpp-seller-express`, `mpp-seller-hono`, `mpp-buyer-fetch`, `mpp-buyer-manual`
Python	`examples.mpp_seller`, `examples.mpp_buyer`, `examples.x402_seller`, `examples.x402_buyer`, `examples.tap_seller`
Go	MPP seller, MPP buyer, x402 seller, x402 buyer, and TAP seller
Rust	`mpp-seller`, `mpp-buyer`, `x402-seller`, `x402-buyer`, `payment-status`, `tap-seller`

Run a Python example from the repository with uv run --locked python -m examples.mpp_seller. Run a Rust example with cargo run --locked -p inflow-examples --bin mpp-seller. Run a Go example with go run ./examples/mpp-seller. mpp-aep-seller-express puts AEP enrollment in front of an MPP endpoint. mpp-card-seller-express accepts USD payments with Visa network tokens. The mpp-seller-express and mpp-seller-hono examples serve these endpoints on http://localhost:3000.

Endpoint	Price in the MPP example
`GET /api/widgets`	0.01 USDC
`POST /api/upload`	0.10 USDC
`GET /api/subscribe`	1.00 USDC for each month
`GET /api/checkout`	1.0 USD or 0.0095 USDC
`GET /free`	Free

AEP and ODP SDKs

Use these SDKs for Step 2 (Enrollment) and Step 3 (Discovery) of the seller integration.

Protocol	Go	Java	Node.js	Python	Rust
ODP	`odp-go`	`odp-java`	`odp-node`	`odp-python`	`odp-rust`
AEP	`aep-go`	`aep-java`	`aep-node`	`aep-python`	`aep-rust`

The ODP SDKs are in the offering-protocol organization on GitHub. The AEP SDKs are in the aep-foundation organization.

Overview

Pay as an agent

Integrate your service

Concepts

Reference

Environments

Node.js and TypeScript

Python

Go

Rust

Feature differences

Examples

AEP and ODP SDKs

​Environments

​Node.js and TypeScript

​Python

​Go

​Rust

​Feature differences

​Examples

​AEP and ODP SDKs

Environments

Node.js and TypeScript

Python

Go

Rust

Feature differences

Examples

AEP and ODP SDKs