LLM Cost Firewall

LLM Cost Firewall is a reverse proxy that detects recursive agent loops and enforces spend caps in RAM.

AI Circuit Breaker is a drop-in reverse proxy that stops runaway autonomous agents before they drain API budgets. It catches infinite tool loops and enforces hard spend caps in volatile RAM with sub-35ms overhead and zero payload retention. The proxy is built in Python and FastAPI, featuring strict zero-payload retention and AES-256 encryption for upstream credentials. It works with any client or framework that sends OpenAI-compatible requests to a custom base URL, including CrewAI, LangChain, LangGraph, AutoGen, and direct REST clients. Developed by Roan de Jager in Norway, the system provides hourly and daily budget caps, sliding-window loop detection, and emergency webhook notifications for production agents.

LLM Cost Firewall at a glance

Best for: Software engineer
Runs on: API, self-hosted
Pricing: Free $0/mo; Pro $29/mo
Released: October 2026
Category: AI agent tool
Website: circuit-breaker-sage.vercel.app

Key features

Detects recursive agent loops in volatile memory
Enforces hourly and daily budget caps
Maintains zero payload retention
Provides OpenAI-compatible proxy endpoint
Sends emergency Slack and Discord webhooks
Encrypts upstream credentials with AES-256
Operates with sub-35ms raw performance

Use it for

Preventing infinite tool retry loops in agents
Enforcing hard spend caps on API budgets
Routing production AI requests securely
Controlling costs for CrewAI and LangChain apps

Alternatives to LLM Cost Firewall

Aw1 Circuit Breaker — Stops prompt bypasses and dynamic execution attacks in under a millisecond.
AgentOps — Track token usage, costs, and traces across 400 plus LLMs and agent frameworks.
MCP Bouncer — Stops agents from exfiltrating data to destinations found in untrusted tool output.
Cloudgrip Backend — Acts as a local circuit-breaker proxy to enforce strict budget caps.
Agentloop — Provides a clean agent loop with provider-agnostic LLM access, hooks, and safety budgets.
AgentGate — Blocks attacks in under 35ms with a local neural classification head.
TaintWall — Enforces deterministic security policies at the tool boundary for AI agents.
Attenuated Agent Budgets — Enables offline sub-budget splitting for agent swarms without crypto rails.
Navige — Cuts AI agent and LLM spend without changing the final output.
Fluxix — Stops dangerous tool calls and data leaks before execution.
SentinelGate — Stops prompt injections and tool hijacks with sub-millisecond overhead.
APIStack — Connect AI agents to over 100 tools using one API key or a single MCP endpoint.

All LLM Cost Firewall alternatives