Overview

Everything you need to integrate Scrawn into your application.

Configuration

scrawn() is the factory that creates your billing instance:

import { scrawn, tag } from "@scrawn/core";

const biller = scrawn({
  apiKey: process.env.SCRAWN_KEY as `scrn_${string}`,
  baseURL: process.env.SCRAWN_BASE_URL || "http://localhost:8069",
  tags: ["PREMIUM_CALL", "EXTRA_FEE"] as const,
  expressions: ["MY_EXPR"] as const,
  retryCount: 3,
});

The factory accepts a single config object:

Param	Type	Default	Description
`apiKey`	`string`	—	Your Scrawn API key (starts with `scrn_`)
`baseURL`	`string`	—	Base URL of your Scrawn backend (e.g. `http://localhost:8069`)
`secure`	`boolean`	`true`	Whether to use TLS for gRPC. Set to `false` for local dev
`tags`	`readonly string[]`	—	Known tag names for compile-time type checking on `biller.tag()`
`expressions`	`readonly string[]`	—	Known expression names for compile-time type checking on `biller.expr()`
`retryCount`	`number`	`2`	Auto-retry attempts on transient network errors. Set to `0` to disable

Functions

The core methods you call in your code to track usage, bill AI tokens, and collect payments.

Usage Tracking

Track billable events — manually with basicUsageEventConsumer() or automatically with middlewareEventConsumer().

AI Token Billing

Meter AI token usage per-call with aiTokenStreamConsumer(), biller.ai(), or trackAI().

Collect Payments

Generate a Dodo checkout link when a user's balance crosses your threshold.

Reference & Guides

Pricing expressions, production patterns, and framework integration.

Pricing DSL

Type-safe expressions for complex pricing — mul(), add(), tag(), inputTokens(), and more.

Production Patterns

Error handling, retries, batch processing, caching, and environment configuration.

Framework Recipes

Quick integration patterns for Express, Next.js, Fastify, NestJS, tRPC, Hono, and Nuxt.