Lakera Guard vs Rebuff
If you are adding a defense layer against prompt injection and jailbreaks, these two show the classic split. Lakera Guard is a commercial API. You send it text and get back a risk verdict. Rebuff is an open-source detector you run yourself. It layers a few detection tricks together.
| Dimension | Lakera Guard | Rebuff |
|---|---|---|
| What it is | Hosted API for injection and safety detection | Open-source injection detector you self-host |
| License | Commercial / hosted | Open source |
| Where it runs | You call their API | Your own infrastructure |
| Detection approach | Managed models the vendor updates | Layered checks including heuristics, an LLM check, a vector store, and canary tokens |
| Who maintains the threat model | The vendor, continuously | You and the community |
| Data leaves your infra | Yes, text goes to their API | No, unless you add an LLM step that calls out |
| Ops burden | Low, it is a managed service | Higher, you run and tune it |
| Best for | Teams who want defense now without maintaining it | Teams who want control and no third-party calls |
You want an injection and jailbreak filter live quickly, and you would rather pay someone to keep the detection current than chase new attacks yourself. Lakera Guard fits when you are fine sending prompt text to a third party and you value a managed, continuously updated defense.
You need to keep prompts on your own infrastructure, you want to read and tune the detection logic, or you want something free to build on. Rebuff gives you a layered starting point you fully own. That is the right call when a third-party API is off the table.
These two are at different stages of maturity. Lakera Guard is a maintained commercial product. Rebuff is a useful open-source project whose momentum has been uneven, so check its recent activity before you build on it. If you need real injection defense in production and can send text to an API, a managed service like Lakera Guard is the easier bet, because the threat landscape moves faster than most teams can track. If you cannot send data out, self-host Rebuff and budget for the upkeep. Do not treat either one as a solved wall. Injection defense is probabilistic and both will miss things, so keep least-privilege tool access and human approval on the dangerous actions no matter which you pick.