TapVow

What It Does

TapVow is an open-source gateway platform that enforces spending limits on AI agents running LLM calls and making x402 stablecoin payments. It acts as a protective layer between your AI agents and API providers, blocking unauthorized spending before any call reaches the provider. You sign a budget with a passkey, and TapVow ensures no agent exceeds that cap — the call over the limit stops before it's sent.

Who It's For

TapVow is built for developers and teams running multiple AI agents in parallel who need ironclad cost controls. If you operate dozens of coding agents, research assistants, or autonomous workflows, TapVow prevents runaway spending incidents like the creator's own 1,000 USD drain in 29 hours.

Key Features & Capabilities

• Signed Budget Mandates: Define a total budget, per-call cap, allowed payees, and expiry, all cryptographically signed with your passkey
• Gateway Architecture: Agents call through TapVow instead of directly to OpenAI, Anthropic, or DeepSeek — every charge is pre-checked
• Multi-Agent Coordination: In testing, 10 agents sharing a 5.00 USD cap stayed under budget (4.97–4.99 USD spent) across 6 runs, while naive counters overran by 4%
• x402 Stablecoin Payments: Support for USDC payments on Base blockchain (testnet validated with 12 successful settlements)
• Signed Receipt Ledger: Every charge and denial is hash-chained and cryptographically verifiable — 26,971 single-character edits were all caught by the verify function
• Non-Custodial: TapVow never holds your money; payments flow directly from your wallet or provider account to the payee
• Prompt Injection Defense: Blocks unauthorized payment attempts, even if an agent is compromised

How It Works

You point your OpenAI-compatible client (Claude Code, Codex, etc.) at the TapVow gateway instead of the provider. Each call is checked against your signed mandate. If it's over the cap, over budget, or to an unknown payee, the call stops before it's signed or sent. You receive a signed, tamper-evident receipt for every transaction.

Current Status & Roadmap

As of October 2026, TapVow has passed 476 tests and settled 59 testnet payments. Mainnet spend is still 0 USD, and the codebase is pre-release (MIT licensed, GitHub pending publication). Stripe integration is planned as the next payment rail.

What Differentiates It

Unlike naive shared counters that can overspend under concurrency, TapVow's gateway architecture enforces hard limits even when dozens of agents call simultaneously. The cryptographic receipt chain and passkey-based mandate signing provide auditability and non-repudiation that basic API proxies lack.