Prompt Compass
Prompt Compass is a lightweight, on-device prompt router and firewall that classifies user prompts before they reach a large language model. The entire model is just 0.57 MB, enabling it to run on phones, browsers, or CDN edge workers without a GPU. It makes routing decisions in approximately 5 milliseconds, determining whether a prompt should be handled by a local cheap model or forwarded to a more powerful cloud model. Simultaneously, it detects personally identifiable information (PII) such as credit card numbers and social security numbers, and blocks jailbreak or prompt injection attempts. By keeping simple prompts local, it can reduce cloud AI costs by up to 96% on assistant-style traffic and 27% on mixed workloads, as measured on public benchmarks. The tool supports English, Spanish, French, German, and Hindi, including disguised and mixed-language text, all within the same tiny model. Prompt Compass is available as a hosted API, on-device SDKs for integration into applications, and dedicated editor commands for VS Code and Open VSX. An upcoming companion product, Agent Compass, will extend safety checks to agent actions such as shell commands and tool calls, currently in private preview.
- Category
- LLM
- Pricing
- Free
Problem solved
Prompt Compass addresses the high cost and security risks of sending every user prompt to expensive cloud LLMs. It routes simple queries to cheaper local models, blocks sensitive PII from being transmitted, and stops jailbreak attacks before they reach the model, all with a single, ultra-fast on-device check.
Use cases
- Route simple customer support queries to a local model to cut cloud costs
- Block credit card numbers, SSNs, and secrets from being sent to LLMs
- Prevent prompt injection and jailbreak attempts in chatbot applications
- Integrate on-device filtering into mobile apps for privacy-preserving AI
- Add prompt safety checks to CI/CD pipelines for LLM testing
- Use as an IDE extension to validate prompts during development
Audience
- Developers
- ML Engineers
- Data Scientists
- Startups
- Enterprise
Pros
- Extremely small model (0.57 MB) fits on any device
- Ultra-fast decisions (~5 ms) with no network round-trip
- Combines routing, PII detection, and jailbreak blocking in one call
- Multilingual support for five languages out of the box
- Privacy-preserving: prompts are never stored or forwarded
Cons
- Limited to five languages currently
- No self-hosted server option; relies on hosted API or on-device SDK
- Free tier may have usage limits (not specified)
- Agent Compass for action safety is still in private preview
- Dependency on a proprietary model with no open-source release
Official website: https://mpcfintech.com/compass
Canonical LambdaBase page: https://www.lambdabase.com/tools/prompt-compass