Guardrail by NeatProxy
The runtime firewall
for AI coding agents.
Guardrail is a local proxy on localhost:4000. It intercepts runaway agent loops, audits silent context taxes, and enforces hard limits
before calls hit provider billing or exhaust your 5-hour subscription quota.
✓ 100% Localhost ✓ Zero Code Telemetry ✓ OAuth & API-Key Modes ✓ Fails Closed by Design
The problem
Agents spend money faster than anyone can watch.
A coding agent runs unattended for minutes at a time, and a single retry loop can burn more than a month of subscription before anyone looks. The tools that exist today tell you afterwards.
Bills arrive late
Provider billing is a monthly rear-view mirror. By the time a number looks wrong, the money is already spent.
Counters only count
A token counter watches the meter run. It has no opinion about when to stop, and no way to act on one.
Alerts are not brakes
A threshold alert fires after the spend it is warning you about. A budget you cannot enforce is a preference.
An illustrative estimate assuming 22% of spend is recoverable waste from retry loops, uncalled MCP tool definitions, and context accumulation. On real traffic we have measured idle cache eviction alone at 19% of spend. Scaled across 12 active developers.
# pricing_model
pay for the cloud, not the firewall.
Guardrail runs free on your machine, with no credit card and no time limit. Pro adds the hosted dashboard, longer history, and sync across every machine you own. Team is one flat plan for the whole group.
// free
Local firewall, budget policies, local dashboard, 7 days of history. No credit card required.
// pro
Everything in Free, plus the hosted dashboard, 90 days of history and sync across machines. $144 yearly.
// team (5 seats)
A flat bundle for up to 5 seats, with an admin console, per-member spend and shared project caps.
// TWO BILLING MODELS. ONE REAL RISK.
Protection whether you pay by the token or by the seat.
Autonomous coding agents behave differently than manual chat interfaces. Guardrail protects your engineering velocity under both billing models.
The Mid-Sprint Lockout Trap
Flat subscriptions aren't infinite. Unattended sub-agent loops and bloated tool context exhaust Anthropic's 5-hour rolling windows in 20 minutes, locking your developers out mid-day.
- •Live 5-hour plan status bar surfaced right under your CLI prompt.
- •Per-server cost attribution that flags uncalled MCP tool definitions draining your quota.
The Surprise $2,000 Invoice
When an agent gets stuck in a recursive retry loop overnight, provider cards are charged instantly. Observability dashboards only notify you hours after the money is already burnt.
- •Pre-send hard dollar caps on
localhost:4000before calls hit the wire. - •Automatic blocking that halts runaway loops without killing in-flight work.
How it works
One command in front of your agent.
Guardrail is a local proxy. It sits between your coding tool and the provider, relays your existing login, and reads only the metadata as requests pass through — so it can show you the spend and stop it before it leaves your machine.
Connect, keyless
One command points your tool at Guardrail and relays your own Claude Code or Codex login. No API key changes hands — nothing to vault or rotate.
It reads the metadata
Every call flows through localhost:4000 byte-for-byte. Guardrail parses model, tokens, cache and cost — never the prompt, the response, or your code.
See it, then cap it
A live local dashboard shows spend, sessions and hidden cost. Set a budget and an over-budget call is blocked before it ever reaches the provider.
The request body is forwarded untouched. Only model, token counts and cost estimates are written locally to 127.0.0.1
What Guardrail controls
Spend control, not another dashboard to babysit.
Six things it does on your machine, with no cloud and nothing leaving your machine. See how each one works.
Control
Budgets that block
Caps on dollars, requests, tokens or requests-per-minute. Over budget, the call is never sent, so it costs nothing.
Visibility
Hidden cost, surfaced
The cache-write tax on a first turn and the reasoning tokens you never see, attributed per request.
Privacy
Keyless and local
It relays your own login, so no key changes hands, and keeps metadata only in a file on your machine.
Coverage
Seven tools, four providers
One proxy for both coding tools, plus any agent framework that speaks the OpenAI Chat Completions API.
Forecast
Know the month before it lands
Spend pace and a projected month-end total from the sessions you have already run.
Flow
Pause without restarting
Flip tracking off and back on from the dashboard. Your tool keeps working throughout.
Why Guardrail is different
Prevention, not reporting.
Most tools in this space observe. Guardrail sits in the request path, which is the only place a budget can actually be enforced.
Provider dashboards
Show you the bill
Accurate and far too late. They are scoped to an account, not to the project or the session that caused the spike, and they cannot stop anything.
Token counters
Show you the meter
Useful for curiosity, limited for control. Watching a number climb does not stop the next request from being sent.
Observability platforms
Analyse after the fact
Rich analysis, but it arrives after the spend, and it usually means sending prompts and responses to a third party to store.
Guardrail
Stops the request
Runs on your machine, in the path, with your own credentials. Policies are evaluated before each call, so an over-budget request is never sent and never billed.
FAQ