Show HN: Butter – A Behavior Cache for LLMs

(butter.dev)

39 points | by edunteman 22 hours ago

10 comments

  • mountainriver 16 hours ago
    I also did computer agents with a vc backed startup, ran into the same issues, and we built a fairly similar thing at one point.

    It’s useful but it has limitations, it seems to only work well in environments that are perfectly predictable otherwise it gets in the way of the agent.

    I think I prefer RL over these approaches but it requires a bit more data.

  • realitysballs 17 hours ago
    Funny, we are working to implement this same logic in our in-house financial categorization agent. When we have a repeat prompt it goes to a json that stores answers and only goes to AI for edge cases.

    It’s a good idea

    • edunteman 16 hours ago
      Awesome to hear you’ve done similar. JSON artifacts from runs seem to be a common approach for building this in house, similar to what we did with the muscle mem. Detecting cache misses is a bit hard without seeing what the model sees, part of what inspired this proxy direction.

      Thanks for the nice words!

  • rajit 15 hours ago
    We spoke to a number of browser agent companies who said deterministic RPA with an AI fallback was their "secret" :)
  • barapa 16 hours ago
    We often will repeat calls to try again. Or sometimes we make the same call multiple times to get multiple answers and then score or merge them.

    Is this used only in cases where you assume the answer from your first call is correct?

    • edunteman 15 hours ago
      I’d love your opinion here!

      Right now, we assume first call is correct, and will eagerly take the first match we find while traversing the tree.

      One of the worst things that could currently happen is we cache a bad run, and now instead of occasional failures you’re given 100% failures.

      A few approaches we’ve considered - maintain a staging tree, and only promote to live if multiple sibling nodes (messages) look similar enough. Decision to promote could be via tempting, regex, fuzzy, semantic, or LLM-judged - add some feedback APIs for a client to score end-to-end runs so that path could develop some reputation

      • toobulkeh 10 hours ago
        I’d assume RL would be baked in to the request structure. I’m surprised OAI spec doesn’t include it, but I suppose you could hijack a conversation flow to do so
  • invisibleink 16 hours ago
    interesting. is the answer not context specific most of the time? even if I ask LLM the same question again and again the answer depends on the context.

    what are some use cases where you need deterministic caching?

  • Jayakumark 16 hours ago
    What local models will it work with ? Also what will be the pricing for local llms?
    • edunteman 15 hours ago
      Good question, I imagine you’d need to set up an ngrok endpoint to tunnel to local LLMs.

      In those cases perhaps an open source (maybe even local) version would make more sense. For our hosted version we’d need to charge something, given storage requirements to run such a service, but especially for local models that feels wrong. I’ve been considering open source for this reason.

  • puppycodes 17 hours ago
    I like the pricing model but I'm skeptical it will last.
    • edunteman 16 hours ago
      I feel the same - we’ll use it as long as we can since it’s customer aligned but I wouldn’t be surprised if competitive or COGs costs force us to change in the future.
  • ronbenton 17 hours ago
    Interesting... is it legal?
    • edunteman 17 hours ago
      I couldn’t see how it wouldn’t be, as it’s a free market opt-in decision to use Butter
      • ronbenton 16 hours ago
        it wouldn't be the first API service to disallow someone from selling a cache layer for their API. After all, this should likely result in OpenAI (or whatever provider) making less money
        • edunteman 15 hours ago
          Ah yes that makes sense, have heard of those cases too but hadn’t put much thought into it. Thanks for pointing it out!
          • RestartKernel 14 hours ago
            I've seen the OpenRouter guys here on HN before, so you can probably ask them what to look out for.
  • banjwoorri 12 hours ago
    [dead]
  • robofanatic 17 hours ago
    So instead of OpenAI I should pay butter?
    • edunteman 16 hours ago
      It’s bring-your-own-key, so any calls proxied to OpenAI just end up billing directly to your account as normal.

      You’d only pay Butter for calls that don’t go to the provider. That’d be a separate billing account with butter.