No spin. Here's exactly what TokenBrake does, what it doesn't, and how it's different from the limits your provider already gives you.
No. TokenBrake runs on your own server. Your provider API key passes straight through to the provider and is never stored, logged, or written anywhere. It keeps only token counts and dollar amounts — never your prompts or responses.
Native limits are account- or workspace-wide and reconcile on a monthly cycle. OpenAI's can lag up to 24 hours; Anthropic's own docs call its spend reading "informational, not transactional"; Gemini's mandatory cap is account-wide and lets up to 10 minutes of overage through. TokenBrake meters every call in real time, per agent, and hard-stops the next call at your budget. See the guides for the details on each.
OpenAI, Anthropic (Claude), xAI (Grok), Groq, DeepSeek, Mistral, Google Gemini, and OpenRouter — including streaming and prompt caching. More on the roadmap; email us to bump one up.
Neither. An "agent" is one labeled stream of AI usage you route through TokenBrake (a bot, a script, a project), regardless of the device it runs on — and there is no limit on how many you monitor and no per-agent charge. The only thing you can ever buy is one commercial licence, once, for the whole company.
Anything running on the same machine whose API base URL you can set — any language, any framework. The proxy binds 127.0.0.1 and is deliberately not reachable from other devices: that way there is no authentication to misconfigure and nothing exposed to your network. Run one per machine.
It cannot meter consumer chat apps like the ChatGPT or Claude mobile apps, which bill through the vendor and can't be proxied by anyone. It's for the API-based AI your business runs, not a way to track someone's personal chat-app use.
Free for individuals, and for any company under 100 people and under $1M revenue — which is almost everyone. Everything unlocked, unlimited agents, no trial clock. Larger companies buy a one-time commercial licence. The source is public and readable; the licence is PolyForm Small Business rather than open source.
Nothing is held back and nothing expires — every feature is in the free version, the safety brake is permanent. Nothing about licensing ever interrupts your traffic — the only things that stop a call are the budget cap and the breaker, which are the features you asked for. The two things worth saying out loud: it is source-available, not open source, and companies over 100 people or $1M revenue need a paid licence. Both are on this page rather than in the small print.
It watches the shape of your traffic rather than the total. A stuck agent sends the same request over and over; a real batch job sends different ones. When repetition and rate are both high, it opens a circuit breaker in seconds rather than waiting for a budget cap to be reached — and a budget cap can't act until the money is already gone.
You don't have to take our word for it: node demo-runaway.mjs simulates one agent stuck from 02:00 to 08:00 with nobody awake. Budget cap alone: $280.01. Breaker: $3.60, tripped in 10 seconds. No API keys, no network, no money — it runs against the real detection code.
Download tokenbrake-beta.zip, unzip it to ~/TokenBrake, and run node proxy.mjs. Zero dependencies, needs Node 24+. Full steps in the docs.
No. If TokenBrake itself faults, it fails open and lets the call through rather than break your production. It's a safety brake that dramatically reduces bill-shock — not a warranty that a bill can never exceed a budget. Keep your provider-side limits on too.
It binds to 127.0.0.1, so it is reachable only from your own machine — there is no network surface to secure and no shared secret to leak. It forwards only to an allowlist of provider hosts, stripping any scheme or host a caller tries to smuggle into the path (SSRF-guarded). It never stores your API keys or your prompts — the loop detection works on hashes, never on the text.
See what your AI is costing you — and what a runaway loop could cost — in the free calculator.
Open the cost calculator →