An agent that can read the internet and sign payments can be talked into paying the wrong party. TollWarden scans each x402 payment before it settles and returns allow, flag or block, with per-check reasons and an Ed25519 signature bound to that exact payment.
Each package below adds that scan to one agent framework as tools the model can call. Every package can also wrap your payment executor so a blocked payment never runs. The LangChain, CrewAI and Vercel AI SDK packages observe what the agent reads on their own, so a payment whose payee came from a prompt-injected page gets caught. With NeMo and AgentKit you pass that text in. The first 100 calls per API key are free, with no signup.
| Framework | Package | Language |
|---|---|---|
| LangChain | langchain-tollwarden | Python |
| CrewAI | crewai-tollwarden | Python |
| Vercel AI SDK | @tollwarden/ai-sdk | TypeScript |
| Coinbase AgentKit | agentkit-tollwarden | Python |
| NVIDIA NeMo Agent Toolkit | nemo-tollwarden | Python |
The TypeScript client and the Python client work in any agent, and npx -y tollwarden runs an MCP server for any MCP-capable one. Point your model at llms.txt for the integration guide, or read the OpenAPI contract.
TollWarden is advisory and non-custodial. It never touches your keys, wallet or funds, and your own systems decide what to do with each verdict.
TollWarden