> ## Documentation Index
> Fetch the complete documentation index at: https://docs.x402.org/llms.txt
> Use this file to discover all available pages before exploring further.

# SDK Features

> Feature parity across TypeScript, Go, and Python SDKs

# SDK Features

This page tracks which features are implemented in each SDK (TypeScript, Go, Python v2).

## Core

| Component   | TypeScript | Go | Python |
| ----------- | ---------- | -- | ------ |
| Server      | ✅          | ✅  | ✅      |
| Client      | ✅          | ✅  | ✅      |
| Facilitator | ✅          | ✅  | ✅      |

### HTTP Framework Integrations

| Role   | TypeScript                      | Go                  | Python          |
| ------ | ------------------------------- | ------------------- | --------------- |
| Server | Express, Hono, Next.js, Fastify | Gin, net/http, Echo | FastAPI, Flask  |
| Client | Fetch, Axios                    | net/http            | httpx, requests |

## Networks

| Network        | TypeScript | Go | Python |
| -------------- | ---------- | -- | ------ |
| evm (EIP-155)  | ✅          | ✅  | ✅      |
| svm (Solana)   | ✅          | ✅  | ✅      |
| avm (Algorand) | ✅          | ❌  | ❌      |
| stellar        | ✅          | ❌  | ❌      |
| aptos          | ✅          | ❌  | ❌      |
| hedera         | ✅          | ❌  | ❌      |

## Mechanisms

| Scheme | Network | `assetTransferMethod` | TypeScript | Go | Python |
| ------ | ------- | --------------------- | ---------- | -- | ------ |
| exact  | evm     | `eip3009`             | ✅          | ✅  | ✅      |
| exact  | evm     | `permit2`             | ✅          | ✅  | ✅      |
| exact  | svm     | -                     | ✅          | ✅  | ✅      |
| exact  | avm     | -                     | ✅          | ❌  | ❌      |
| exact  | stellar | -                     | ✅          | ❌  | ❌      |
| exact  | aptos   | -                     | ✅          | ❌  | ❌      |
| exact  | hedera  | -                     | ✅          | ❌  | ❌      |
| upto   | evm     | `permit2`             | ✅          | ✅  | ✅      |

## Extensions

| Extension                            | TypeScript | Go | Python |
| ------------------------------------ | ---------- | -- | ------ |
| bazaar (server)                      | ✅          | ✅  | ✅      |
| bazaar (facilitator client - list)   | ✅          | ✅  | ✅      |
| bazaar (facilitator client - search) | ✅          | ✅  | ✅      |
| sign-in-with-x                       | ✅          | ❌  | ❌      |
| payment-identifier                   | ✅          | ✅  | ✅      |
| offer-receipt                        | ✅          | ❌  | ❌      |
| eip2612-gas-sponsoring               | ✅          | ✅  | ✅      |
| erc20-approval-gas-sponsoring        | ✅          | ✅  | ✅      |

## Client Hooks

| Hook                     | TypeScript | Go | Python |
| ------------------------ | ---------- | -- | ------ |
| onBeforePaymentCreation  | ✅          | ✅  | ✅      |
| onAfterPaymentCreation   | ✅          | ✅  | ✅      |
| onPaymentCreationFailure | ✅          | ✅  | ✅      |
| onPaymentResponse        | ✅          | ✅  | ❌      |
| onPaymentRequired (HTTP) | ✅          | ❌  | ❌      |

## Server Hooks

| Hook                      | TypeScript | Go | Python |
| ------------------------- | ---------- | -- | ------ |
| onBeforeVerify            | ✅          | ✅  | ✅      |
| onAfterVerify             | ✅          | ✅  | ✅      |
| onVerifyFailure           | ✅          | ✅  | ✅      |
| onBeforeSettle            | ✅          | ✅  | ✅      |
| onAfterSettle             | ✅          | ✅  | ✅      |
| onSettleFailure           | ✅          | ✅  | ✅      |
| onVerifiedPaymentCanceled | ✅          | ✅  | ❌      |
| onProtectedRequest (HTTP) | ✅          | ✅  | ❌      |

## Facilitator Hooks

| Hook            | TypeScript | Go | Python |
| --------------- | ---------- | -- | ------ |
| onBeforeVerify  | ✅          | ✅  | ✅      |
| onAfterVerify   | ✅          | ✅  | ✅      |
| onVerifyFailure | ✅          | ✅  | ✅      |
| onBeforeSettle  | ✅          | ✅  | ✅      |
| onAfterSettle   | ✅          | ✅  | ✅      |
| onSettleFailure | ✅          | ✅  | ✅      |

## Extension Hooks

| Hook                          | TypeScript | Go | Python |
| ----------------------------- | ---------- | -- | ------ |
| enrichDeclaration             | ✅          | ✅  | ✅      |
| enrichPaymentRequiredResponse | ✅          | ❌  | ❌      |
| enrichSettlementResponse      | ✅          | ❌  | ❌      |

## Hook Adapter Features

| Feature                                 | TypeScript | Go | Python |
| --------------------------------------- | ---------- | -- | ------ |
| Scheme-level lifecycle hook adapters    | ✅          | ✅  | ❌      |
| Extension-level lifecycle hook adapters | ✅          | ✅  | ❌      |

## MCP (Model Context Protocol)

| Feature                        | TypeScript | Go | Python |
| ------------------------------ | ---------- | -- | ------ |
| MCP server payment wrapper     | ✅          | ✅  | ✅      |
| MCP client (auto-pay tools)    | ✅          | ✅  | ✅      |
| Bazaar discovery for MCP tools | ✅          | ✅  | ✅      |

## HTTP Server Features

| Feature              | TypeScript | Go | Python |
| -------------------- | ---------- | -- | ------ |
| dynamicPayTo         | ✅          | ✅  | ✅      |
| dynamicPrice         | ✅          | ✅  | ✅      |
| paywall (browser UI) | ✅          | ✅  | ✅      |