Forsig Proxy Quickstart

Forsig is an OpenAI-compatible proxy that enforces budgets, model allowlists, velocity caps, and a circuit breaker. You call Forsig the same way you call OpenAI—just change the base URL and set your Forsig allowance key as the API key.

Environment variables

export OPENAI_BASE_URL="https://YOUR_WORKER.workers.dev"
export OPENAI_API_KEY="sk_allow_xxx"

Node.js example

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,        // your Forsig allowance key
  baseURL: process.env.OPENAI_BASE_URL,      // your Forsig worker URL
});

const res = await client.chat.completions.create({
  model: "gpt-4o-mini",
  messages: [{ role: "user", content: "Hello from Forsig" }],
});

console.log(res.choices[0].message.content);

Python example

from openai import OpenAI
import os

client = OpenAI(
  api_key=os.environ["OPENAI_API_KEY"],
  base_url=os.environ["OPENAI_BASE_URL"],
)

res = client.chat.completions.create(
  model="gpt-4o-mini",
  messages=[{"role":"user","content":"Hello from Forsig"}],
)

print(res.choices[0].message.content)

Idempotency

Set Idempotency-Key to safely retry without double-charging.

Headers Forsig adds

• X-Allowance-Agent-Id
• X-Allowance-Reserved-Cents
• X-Allowance-Cost-Cents
• X-Allowance-Balance-Cents
• X-Forsig-Request-Id

Common error codes

• insufficient_balance
• velocity_cap_exceeded
• circuit_breaker_tripped
• model_not_allowed
• key_frozen