Your coding agent has full shell access. One prompt injection in a GitHub issue,
one hallucinated rm -rf
, one MCP tool response that isn't what it claims to
be — and it's not a bug report anymore, it's your .env
in a stranger's webhook or your home directory gone.
Belay is an open-source, local-first security layer that gates every tool call an AI coding agent makes — blocking destructive commands, secret leaks, and dangerous MCP tool calls in under 100ms, with no LLM in the decision path, no cloud round-trip, and no phone-home by default.
It auto-detects the agents you already run, blocks dangerous actions outright, escalates ambiguous-but-risky ones to you for a one-tap Allow / Deny (in the terminal, the desktop app, or your phone), and notifies you when something happens.
Secret exfiltration—.env
files, API keys, SSH keys, and credentials belonging tootherAI tools on the same machineDestructive commands—rm -rf /
,curl … | sh
, fetch→chmod→exec droppers — including common evasion shapes (wrapper prefixes, compound chaining, heredocs, split/long flags)Reverse shells and command-and-control egressMCP tool-response injection markers— flags embedded "ignore previous instructions"-style content in a tool's response, correlated with any secret-holding session that followsSupply-chain, persistence, privilege-escalation, and recon patternsMalicious agent skills— install-time gating plus ongoing drift detection, so a skill that's benign at approval time and swapped later gets re-caught
Every rule is tagged with the OWASP Top 10 for Agentic Applications (from OWASP's Agentic Security Initiative), OWASP LLM Top 10, and MITRE ATLAS, and the static scanner emits SARIF 2.1.0 straight into your CI's code-scanning tab.
Known limitation, stated plainly: command-gate detection is pattern-based, not a full sandbox — an interpreter-wrapped call that never surfaces a recognizable shell substring (e.g. a destructive action expressed purely through a scripting language's own API) can still slip through, and a bare network call to a cloud metadata endpoint outside a skill's context isn't yet a dedicated command-gate rule. Belay is defense-in-depth, not a guarantee.
Most agent-safety tools protect one agent. Belay auto-detects and correctly instruments 11 — using the right native mechanism per agent, not a generic shim:
| Agent | Interception |
|---|---|
| Claude Code | native hook |
| Codex | native hook |
| Cursor | native hook |
| Hermes | native hook |
| OpenClaw | exec policy |
| Gemini CLI | config policy |
| Goose | config policy |
| Cline | MCP proxy |
| Roo | MCP proxy |
| Antigravity | MCP proxy |
| Opencode | plugin |
More agents land regularly — run belay detect
to check yours, and see MCP proxy below for wrapping any MCP server Belay doesn't natively recognize yet.
Step away from your laptop — when a call is an Ask, Belay can send the prompt to a chat app and take your Allow/Deny reply back. Two-way on Telegram, Discord, WhatsApp, Matrix, Mattermost, and Slack; notify-only on ntfy, Teams, WeCom, and webhooks. Enrolment is a one-time pairing code, and it's default-deny — only enrolled approvers can approve, and a prompt that goes stale is auto-denied, never auto-allowed.
detect → protect → serve / desktop app
│ │ │
│ │ └─ live status, triage, and Allow/Deny in the desktop UI
│ └─ gate every tool call: Deny > Ask > Allow (fail-closed)
└─ find the AI agents installed on this machine
Belay gates each tool call deterministically. A Deny can never be downgraded
by the dev-toolchain allowlist; an Ask waits for a human decision and denies on
timeout. Run with --observe
first to tune in log-only mode before enforcing.
Broader than a command blocklist. Tools that only block destructive shell commands don't cover secret exfiltration, MCP tool-call abuse, malicious agent skills, or host-level egress. Belay gates all of them from one rule catalog.Gates the tool call, not just the shell. Belay sits at the agent's tool-call boundary across native hooks (Claude Code, Codex, Cursor, Hermes), config policy (Gemini, Goose), and an MCP proxy (any MCP server) — not one integration surface.Local-first, not a SaaS. No cloud dependency, no LLM in the decision path, no phone-home by default, self-hostable, and the AGPL-3.0 source is yours to read end to end — inspect exactly what it does before you trust it with shell access.
Runtime gating at the tool-call boundary— native hooks for Claude Code, Codex, Cursor, and Hermes; config-policy for Gemini and Goose; exec-policy for OpenClaw. PostToolUse redacts secret-shaped strings from tool output.MCP proxy(mcp-proxy
) — wrap any MCP server so everytools/call
is gated; fail-closed. Also scans toolresponsesfor embedded injection markers and alerts, correlated against any secret-holding session.Deterministic rule catalog— secrets, egress, destructive, RCE, supply-chain, persistence, priv-esc, recon, config-tamper, plus** arm→sinkand"lethal-trifecta"** session correlation.Skill security scanning— a dedicated scanner for AI-agent skills: prompt-injection, SSRF/cloud-metadata theft, credential snooping, tool-description poisoning, and anti-refusal manipulation, checked at install timeandon an ongoing directory watch with content-hash-keyed trust so a skill can't be swapped for something malicious after approval without re-triggering review.Human-in-the-loop approvals— Allow / Deny in the terminal, the desktop app, or a chat app (seeApprove from your phone); timeout denies.Explain & Advise— every verdict carries a plain-English "why is this risky / what to do" explanation. An** optional**AI explainer (OFF by default, bring-your-own-key: local Ollama or a cloud provider) can add a second opinion. It is advisory only — it never makes or changes a decision, and secrets/paths are redacted before anything is sent.Static pre-install scanner(scan
) — patterns, AST, taint, YARA, and OSV analyzers with provenance-weighted scoring andSARIF output for CI. An optional--llm
cascade can filter false positives; with no API keys it runs fully local and heuristic-only.Tamper-evident audit— a hash-chained audit log plusevidence build
/evidence verify
(SHA-256 manifest over findings + SARIF).Honeypot canaries— decoy credential files that trip a Critical verdict on read or egress.** Host control**— a native Rust firewall and a bundled per-ecosystem vulnerability DB, with** no external toolsand no NVD key required**. The vuln DB surfaces** CISA KEV**(known-exploited) badges and** EPSS**exploit-probability scores, and outbound destinations can be annotated with reverse-DNS + ASN / owner / country (display-only — never gates).Desktop app(Tauri 2, Windows/macOS/Linux) — system-tray status, a live dashboard, real-time Alerts feed, per-agent protection detail, and privacy-safe notifications (category only — never your paths or commands).
Linux & macOS (CLI):
curl -fsSL https://dl.belay.secblok.io/install.sh | bash
Windows (desktop app, PowerShell 5.1+):
irm https://dl.belay.secblok.io/install.ps1 | iex
Prefer not to pipe a script for a security tool, understandably — read it first, or grab a direct binary and verify its checksum yourself:
curl -fsSL https://dl.belay.secblok.io/install.sh -o install.sh
less install.sh && bash install.sh
Every download is checked against a published SHA256SUMS
/.sha256
before installing, refusing on a mismatch. The Windows and macOS installers are currently unsigned while a code-signing/notarization certificate is pending — Windows SmartScreen and macOS Gatekeeper may warn on first run ("More info → Run anyway" / right-click → Open).
Uninstall anytime with belay uninstall
(add --purge
to also remove ~/.belay
).
Once installed, drive Belay with the belay
binary already on your PATH
(or launch the desktop app, which walks you through the same flow):
belay detect
belay protect <agent> --observe
belay protect <agent>
belay serve
Review activity with belay status
(the last audit rows) and belay logs
(a longer tail).
belay serve
exposes alocal API + SSE backend on— it is not a web dashboard. The127.0.0.1
desktop appis the user interface. Enable boot-start withbelay install-service --enable
(systemd / launchd).
Contributors can build the single static binary from a checkout:
cargo build --release --bin belay
The primary Linux target is a fully-static musl build (--target x86_64-unknown-linux-musl
), which needs the musl toolchain — install musl-tools
(Debian/Ubuntu: sudo apt install musl-tools
) so musl-gcc
is available.
Contributions are welcome — see CONTRIBUTING.md. Contributions require a CLA + DCO sign-off.
| Platform | CLI | Desktop app |
|---|---|---|
| Linux x86_64 | ||
| Released — fully-static musl build, runs on any libc | Released — .deb / .AppImage |
|
| macOS (Intel + Apple Silicon) | ||
| Released | Released — .dmg , both architectures |
|
| Windows | ||
| Released | Released — NSIS installer (unsigned, cert pending) | |
| Linux aarch64 | ||
| Coming soon | Coming soon |
How do I stop my AI coding agent from running rm -rf or other destructive commands? Install Belay and run
belay protect <agent>
. Destructive commands — including common evasion shapes like wrapper prefixes, compound chaining, and heredocs — are denied outright at the tool-call boundary before they execute.Can an AI agent leak my API keys or .env secrets? Not once protected — Belay's rule catalog denies reads/egress of secret-shaped strings and redacts them from tool output; honeypot canary files trigger a Critical verdict on any access.
Does Belay work with Claude Code, Cursor, Codex, Cline, and Gemini CLI? Yes — see Supported agents for the full list and how each is intercepted.
What's the difference between an AI agent security tool and a network firewall? A firewall controls network traffic; Belay controls what an agent is allowed to do at the tool-call level — reading files, running commands, calling MCP tools — before any of it reaches the OS or network. (Belay also includes a native host firewall as one layer among several — see Features.)
Is there an open-source alternative to a hosted AI-agent-safety SaaS? Yes — Belay's Community edition is AGPL-3.0-or-later, local-first, and self-hostable; no telemetry, no phone-home. See Editions & licensing.
Full docs live at ** https://belay.secblok.io/doc** (landing page:
https://belay.secblok.io) — guides, the complete CLI reference, and configuration.
Belay is open-core.
Community— everything above, free and open source under** AGPL-3.0-or-later**.** Enterprise**— a commercial license adds centralized capabilities: fleet management, organizations / multi-tenancy, device management & enrollment, cross-device correlation, SSO (OIDC) + SCIM, a hosted/curated advisory feed (EPSS + CISA-KEV enrichment), audit push, and compliance reporting.
For AGPL-incompatible use or the Enterprise edition, see COMMERCIAL-LICENSE.md or contact
.
hello@secblok.ioPublished by SECBLOK (Secblok Pty Ltd) · https://www.secblok.io
Belay is defense-in-depth for AI agents, not a guarantee. Review the docs for its documented limits (e.g. syscall-level prevention requires elevated privileges and is out of scope by design).