> ## Documentation Index
> Fetch the complete documentation index at: https://shinydapps-bd9fa40b.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Agent SDK — Quickstart
> Let your AI agent pay L402-protected APIs automatically. Blink or Alby wallet, budget control, MCP and LangChain ready.
## What this does
l402-kit ships a built-in **client** that lets any AI agent — or any script — call L402-protected APIs without writing the payment loop yourself.
```
Agent → GET /api/data
API → 402 + BOLT11 invoice
Agent → pay invoice (Blink / Alby)
Agent → GET /api/data Authorization: L402 macaroon:preimage
API → 200 ✓
```
Everything in between — invoice parsing, wallet call, retry — is handled automatically.
***
## Node.js / TypeScript
### 1. Install
```bash theme={null}
npm install l402-kit
```
### 2. Pick a wallet
Get credentials at [dashboard.blink.sv](https://dashboard.blink.sv) → API Keys.
```typescript theme={null}
import { L402Client, BlinkWallet } from "l402-kit";
const client = new L402Client({
wallet: new BlinkWallet(
process.env.BLINK_API_KEY!,
process.env.BLINK_WALLET_ID!,
),
budgetSats: 1000, // max spend per session
});
const res = await client.fetch("https://api.example.com/premium");
const data = await res.json();
console.log(data);
```
Get your access token at [getalby.com](https://getalby.com) → Settings → Access Tokens.
```typescript theme={null}
import { L402Client, AlbyWallet } from "l402-kit";
const client = new L402Client({
wallet: new AlbyWallet(process.env.ALBY_TOKEN!),
budgetSats: 1000,
});
const res = await client.fetch("https://api.example.com/premium");
const data = await res.json();
console.log(data);
```
***
## Python
### 1. Install
```bash theme={null}
pip install l402kit
```
### 2. Call the API
```python theme={null}
import os
from l402kit import L402Client
from l402kit.wallets import BlinkWallet
client = L402Client(
wallet=BlinkWallet(os.environ["BLINK_API_KEY"], os.environ["BLINK_WALLET_ID"]),
budget_sats=1000,
on_spend=lambda sats, url: print(f"Paid {sats} sats → {url}"),
)
r = client.get("https://api.example.com/premium")
print(r.json())
```
```python theme={null}
import os
from l402kit import L402Client
from l402kit.wallets import AlbyWallet
client = L402Client(
wallet=AlbyWallet(os.environ["ALBY_TOKEN"]),
budget_sats=1000,
)
r = client.get("https://api.example.com/premium")
print(r.json())
```
***
## What happens step by step
1. `client.fetch` / `client.get` sends the request without any auth header
2. If the API returns `402`, the client reads the `invoice` and `macaroon` from the response body (or `WWW-Authenticate` header)
3. It checks your budget — throws `BudgetExceededError` if the price would exceed the limit
4. It calls `wallet.payInvoice(bolt11)` and waits for the preimage
5. It retries the request with `Authorization: L402 :`
6. Returns the final `Response`/`httpx.Response` to your code
No 402? The response is passed through untouched.
***
## Spending report
```typescript theme={null}
// TypeScript
const report = client.spendingReport();
// { total: 42, remaining: 958, byDomain: { "api.example.com": 42 }, transactions: [...] }
```
```python theme={null}
# Python
report = client.spending_report()
print(f"Spent {report.total} sats, {report.remaining} remaining")
```
***
## Next steps
Blink, Alby — full setup and options
Per-domain limits, callbacks, reports
Claude Desktop integration in 2 minutes
Drop-in tool for LangChain agents