Launch HN: Bullet (YC S26) – A Faster Coding Agent (codewithbullet.com)
64 points by adi1 13 hours ago
Hi HN! We’re Adi and Alex, founders of Bullet, a faster coding agent.
Bullet started in a senior year dorm. We were fresh out of working at AppLovin and Citadel, and naturally thought we were on a sure path to startup success. We were going to use our skills optimizing stock pricing calculation speeds and agent document context to take over the world. So, Bullet started as an AI hedge fund, a browser-use agent, synthetic financial data (oof), a mobile IDE, and a bunch of other things. We wanted to build something people wanted, but it seemed like everything we built was just terrible, useless, or both.
So, we decided to do something completely different, something completely out of the blue, something that no one had ever done before. Solve a problem we actually had.
Over the course of six pivots, we suffered. Throughout all of our adventures, one final boss kept getting in our way. Claude Code and his little brother Codex. We were spending hours waiting for coding agents like Claude Code and Codex, and got so frustrated to the point that I downloaded the Claude Code whip. We had spent months of time waiting for six codebases-worth of useless coding agent work.
Lightbulb moment. There’s nothing more noble than destroying the institutions! Let’s take on Claude Code and Codex, we can do it! Piece of cake!
And so, Bullet started off as a side project. We used the Claude Code to improve the Claude Code:
1. Model routing. Do you regret giving a task to Fable when it could have literally been done by Sonnet?
2. Targeted code + context search. We think embedding the whole repo is dumb. We also think sticking the whole context (or compressed context) in chat is dumb. So we do faster and better greps over both.
3. Aggressive context hygiene. Tool output is bounded, stale screenshots disappear, we don’t re-read files…the garbage never floods the model.
4. Efficient turns. Batch independent investigation, make one surgical edit, then perform one focused verification. Internal measurement showed 16% fewer round trips and 27% lower cost.
5. The Flash. We prayed to Barry Allen for speed.
And thank the Flash, he gave us speed! On SWE-bench Verified, Bullet resolved 479/500 (95.8%) in one attempt, averaging 119s per task, 35–67% faster than mini-SWE-agent + Fable/Sol depending on task. Full results and methodology here (https://www.codewithbullet.com/blog/benchmark-results.html)
Eventually we started using it every day and never went back.
Listed above were just some of the things about Claude Code that frustrated us the most, but we are constantly optimizing every day (look at that, maybe we did learn something from our jobs).
In our development, the biggest insight was that model speed matters less than reducing round trips. Independent searches, reads, and commands should happen in parallel, while dependent editing and verification stay sequential. One surprising obstacle was code search, small issues like regex-dialect mismatches caused silent misses and sent agents down completely wrong paths, so we built targeted search with fallbacks and bounded context. The most interesting use case so far has been long iterative work (like benchmarks, data pipelines, and evaluation loops), where each step depends on the last and running multiple agents can’t help as much.
Here’s the video demo (https://www.youtube.com/watch?v=rWVmG5fRKgE)
We hope that you guys try out Bullet if you are suffering with speed as much as we were, and we hope it brings you joy, rainbows, and faster responses. And if it’s terrible, let us know it’s terrible (we’re masochists btw)! We'll be in the comments all day, you can also contact us at bullet@davidhf.com.
You can try it at https://codewithbullet.com.
P.S: we hid a code on the website, see if you can unlock the secret page at the footer, all built with Bullet
seizethecheese 4 hours ago
This is a promising direction! Unfortunately, I think the benchmark result here is essentially meaningless.
I recently discovered this same lesson the hard way. I was trying to get a multi-agent system I was building to improve upon GPQA Diamond scores (system here: http://pellmell.ai). No matter how hard I tried, I could not get any lift. When Fable 5 dropped, it also did not improve upon Opus, and I realized my mistake. The benchmark was saturated!
Now, looking at the result here, I see a similar pattern. Fable is not better than Opus, and the score is ~95%. Notably, this post omits which subagent is being used. Why? An intellectually honest way to tell if this thing really works would be to run that agent and report its score and cost as well.
Going back to my GPQA Diamond lesson, you can see here how a saturated leaderboard behaves https://artificialanalysis.ai/evaluations/gpqa-diamond. Fable gets 92.6% for $0.22 per task while several models score higher for $0.01. I could easily publish a router that “enhances Fable on GPQA Diamond” showing improved score for lower cost, just by implementing a router that picks the model at random!
adi1 4 hours ago
The breakdown with which model, per-task cost, and methodology is in the "Full results and methodology" link in the post, not omitted. Definitely check it out if you haven't.
On the saturation point, we agree that a 95.8% result on a mature benchmark isn't the main proof, which is why we're currently running against harder, less saturated benchmarks like Terminal-Bench, CursorBench, and SlopCodeBench (going to publish results on these hard benchmarks shortly). Apart from current user experiences, that will show the value of our harness.
seizethecheese 4 hours ago
I did read "Full results and methodology". It doesn't seem to show which agents you are routing to. Am I missing something? And how do those agents score on SWE-Bench Verified?
alsima 3 hours ago
seizethecheese 4 hours ago
The same thing holds for speed. I could build a system that speeds up Fable on GPQA Diamond ~50%, while improving score, by literally randomly selecting between Fable and Gemini 3.7 Flash. (Solve time for Flash is 0.1min and 0.8min for Fable, with Flash having a better score.)
Hell, I could publish better score at 87.5% time reduction by having the router always pick Flash!
alsima 3 hours ago
Like I mentioned, we omitted routing from the benchmark and evaluated with our strongest model modality. Also, randomly selecting between Fable and Gemini 3.7 Flash wouldn't preserve quality.
seizethecheese 2 hours ago
etchalon 8 minutes ago
Since I can't get this thing not to annotate its commits with itself as an author, I can't use it.
That should be an option, not forced.
retropragma 28 minutes ago
does your harness support ACP?
apimade 12 hours ago
Skip signup:
Cmd+Option+I > Console > 'allow pasting'
const onboarding = document.querySelector('#onboarding'); const app = document.querySelector('#app'); onboarding.style.setProperty('display', 'none', 'important'); app.inert = false; app.removeAttribute('aria-hidden'); document.querySelector('#prompt')?.focus();
Also, warning:
# Share chats with Bullet — helps us improve model routing and answer quality
Enabled by default.
alsima 11 hours ago
Thanks for bringing this up and trying it out! We've disabled Cmd+Option+I in the new version and also have a message during signup about sharing chats with Bullet, let us know if you run into any other issues!
poly2it 5 hours ago
> We've disabled Cmd+Option+I in the new version
Bulletproof.
xrisk 5 hours ago
0kk33 4 hours ago
Congrats on the launch. I can't find which model providers are supported? Are you calling the claude-code CLI directly and make bullet usable with anthropic subscriptions like orca or herdr?
I guess however this is a harness and it needs to connect to the API?
adi1 4 hours ago
Thanks! We support a variety of model providers (OpenCode/Codex/Grok/Claude) via their subscriptions and API keys. This can be seen in the app.
myshapeprotocol 6 hours ago
Focusing on execution speed for coding agents is the right bottleneck to tackle. Exciting launch.
adi1 6 hours ago
Thank you!
hmokiguess 5 hours ago
> P.S: we hid a code on the website, see if you can unlock the secret page at the footer, all built with Bullet
Is it even hidden when your AI ends up tagging it with `aria-label="Hidden secret code"`? Lol. Fun mini game.
adi1 5 hours ago
haha fair enough, surprisingly people still struggle to find it, glad you found it and liked the game!
drxcliu an hour ago
It just works like magic!
alsima an hour ago
Thank you!
esafak 3 hours ago
I think this adds no value. I would stick to OpenCode.
Things I would value: high-fidelity visualization (bonus points for Figma-like visual edits), good tool use (don't force me to tell the model), token efficiency, resource efficiency. Things that are not problems:
* Routing: OpenCode predefines subagents that you can set to appropriate models. * Search: there are AST and embedding-based search MCPs. I use https://github.com/DeusData/codebase-memory-mcp
alsima 3 hours ago
Thanks for the feedback, we do focus on good tool management, context efficiency, etc. As for routing, ideally it isn't the user who has to route themselves, but a layer that routes for them.
Thanks for the link to the repo! We have looked at things like https://github.com/Graphify-Labs/graphify but haven't had a chance to rigorously evaluate their speed boosts on our harness.
tontinton 5 hours ago
Are you freaking kidding me with YC throwing money at something like this? I guess I can fund raise just by having built https://maki.sh, and months ahead of other founders too...
Supermancho 5 hours ago
I'm not sure why anyone would fund "creating an agent". OpenCode is competing with Codex and Claude already.
"The bullets" are not any different than other new agent projects. New agent projects pop up and die constantly and it's not from a lack of funding.
alsima 3 hours ago
I think that if there are many players in the space, it's a problem worth working on! Like I said in the post, our main problem is speed and that's what we're trying to fix. It's been a problem, and it still is a problem. We have tried tools like OpenCode, Pi, etc. but for our speed issue, it did not fix it. If we go down dying on this boat, so be it, at least we went down dying on a problem we care about!
docheinestages 5 hours ago
YCombinator's investments are unfortunately very questionable nowadays.
tomhow an hour ago
People were saying that about YC in 2009, when Airbnb and Stripe were funded. YC’s philosophy has always been to invest in a great many companies, accepting that you can’t know in advance which will succeed, most will fail, but the ones that succeed will be successful enough to pay for all the losses.
docheinestages 5 hours ago
Your landing page is very hard to read. The font size is literally 10px for some content, while animations distract the reader.
Dear YC, please force the startups to dedicate some of the 500k funding for standard web design.
KellyCriterion 4 hours ago
++1 Your comment was the solely reason why I clicked on their page! :-D
Looks like "Techno music design of the 90s" or similar :-D
alsima 3 hours ago
We'll get on that :)
waingake 3 hours ago
lucasdimarco 4 hours ago
I recently switched over to using primarily Bullet for my projects and the speed of it makes it very nice to get projects off the ground quickly and work properly. I also found that Adi and Alex make updates very regularly based on some of the feedback i've submitted to their feedback tab. Good work on this product guys! I'm excited to see how it develops in the future.
adi1 3 hours ago
Thanks Lucas, appreciate the feedback as always!