Agent tools
should be
trustworthy.
We built FunctionFly so AI agents can call any function and know — not hope — that it's safe, signed, and behaving as advertised. Trust is technical, not metaphorical.
Every tool an agent calls is a leap of faith
Today, AI agents call functions — email senders, payment processors, database queries — with no way to verify those functions do what they claim. There's no trust infrastructure: no verification, no attestations, no execution history, no trust scores.
Existing platforms treat tools as dumb endpoints. Define the API, the agent calls it, whatever comes back is accepted. But in a world where agents act autonomously on your behalf, that gap is not just a technical problem — it's a security and reliability crisis waiting to happen.
FunctionFly is the trust layer
A complete trust infrastructure for AI agent tool usage — from publication to execution to trust score.
Publish & Verify
Publish a function with a manifest describing its behavior, capabilities, and intended use. Submit to automated verification — static analysis, fuzzing, signature checks — and human attestation for higher trust tiers.
Sandbox Execution
Every function call runs in an isolated WebAssembly sandbox with declared capabilities enforced at runtime. No filesystem access, no network egress, no privilege escalation — unless explicitly granted.
Trust Scores
Every execution feeds into a live trust score. Functions that run successfully thousands of times earn higher scores. Agents can set policy thresholds and refuse to call functions below a given tier.
Zero-Knowledge Vault
Store API keys, secrets, and sensitive config in the FunctionFly Vault. Encryption and decryption happen client-side — the server never sees your plaintext or your passphrase.
The principles behind every decision
Deny-by-default capabilities
Every capability — network access, filesystem read/write, environment variable exposure — must be declared at publish time and is enforced at runtime by the sandbox.
Trust is earned, not claimed
Trust scores are computed from real execution outcomes. A function that has run 50,000 times with a 99.97% success rate has a measurably different trust profile.
Multi-level verification
Functions can submit to automated checks and human attestation for higher trust tiers. Verification is ongoing, not one-time.
Observability is not optional
Every function call is recorded: input, output, latency, cost, trust score delta, and failure mode.
Multi-language, no rewrites
Write functions in Python, Go, Rust, JavaScript, TypeScript, or WebAssembly. One SDK, every runtime.
Zero-knowledge by design
The server stores only ciphertext, IV, salt, and auth tag — it cannot decrypt your secrets.
What we stand for
Six beliefs that shape every product decision, every architectural choice, and every line of code we ship.
Trust is technical
We build measurable signals — verification levels, execution history, signed attestations, trust scores — that agents can audit programmatically.
Safe by default
Every function runs with the minimum capabilities it needs — nothing more. No ambient authority, no implicit permissions.
Agent-native from day one
FunctionFly was designed for agents to discover, evaluate, and call functions — with manifests, trust filters, and policy routing built in.
Measurable, not magical
Trust tiers are earned through verifiable evidence — not self-attestation or marketing language.
Multi-language, no rewrites
Write in Python, Go, Rust, JavaScript, TypeScript, or WASM. One SDK, every runtime.
Full observability
Execution traces, audit logs, latency breakdowns, cost attribution, and trust score history.
How we got here
Founded
FunctionFly incorporated in Wyoming, headquartered in Fort Worth, TX. Began building the trust layer for AI agents.
Beta Launch
Public beta with multi-language SDKs for Python, Go, Rust, JavaScript, and TypeScript. Released the function registry API and Zero-knowledge Vault.
Today
FunctionFly powers trust for agents across production deployments. 5 language runtimes, 4 trust tiers, 12 global regions, billions of function calls processed.
Ready to build with
trust infrastructure?
Whether you're building agent tooling, evaluating trust infrastructure, or just want to understand how FunctionFly works — get started in minutes.
No credit card required. Free tier includes 25K requests/month and 3 functions.