Bonsai by Jane Street
Hacker ApprovedThe most recommended of 3 UI libraries
Free OCaml UI library and voxel engine people praise for clean, from-scratch code and fun incremental rendering; critics find its look dated and unpolished.
Free OCaml UI library and voxel engine people praise for clean, from-scratch code and fun incremental rendering; critics find its look dated and unpolished.
30 people gave an opinion
- recommend it
- 27
- criticize it
- 3
- approval share
- 90%
Recommended in 8 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: not recommended
- March 2026: not recommended
- April 2026: not recommended
- May 2026: not recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: recommended (month in progress)
Owned for 10 years
Median of the 3 owners who said how long they have had it.
Each square is one year.
Why it carries the badge
- 27 people recommend itNeeds 10 or more, met.
- 9 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 8 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Impressive voxel engine results
“Wow, unbelievably cool. Good luck with the new game using the engine”
Comment from 14 Sep 2026 in “Ask HN: What are you working on? (September 2026)” “it's getting pretty close to being shadertoy for voxels”
Comment from 10 Nov 2025 in “Ask HN: What Are You Working On? (Nov 2025)” “That scale and view-distance..wow!! Brilliant work..”
Comment from 14 Sep 2026 in “Ask HN: What are you working on? (September 2026)” - Comment from 14 Sep 2026 in “Ask HN: What are you working on? (September 2026)”
Readable source, few dependencies
“The docs are a bit sparing but if you read the source its pretty cool to see how they did this.”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library” “It's written completely from scratch, and depends on nearly nothing external.”
Comment from 1 Oct 2026 in “Ask HN: Who wants to be hired? (October 2026)” Useful editor and Blender rendering
“Probably the most interesting thing about it at the moment is the editor.”
Comment from 14 Sep 2026 in “Ask HN: What are you working on? (September 2026)” “Strong plus is that you can render views of the finished room in Blender.”
Comment from 19 Nov 2025 in “Blender 5.0” Screenshots look awesome
“the look and aesthetic of some of your screenshots is awesome”
Comment from 17 Dec 2025 in “Bonsai: A Voxel Engine, from scratch” “it appears that this person totally nailed it”
Comment from 17 Dec 2025 in “Bonsai: A Voxel Engine, from scratch”
What people warn about
Each mark is one comment
Dated, unpolished look
“Everything looks like it's straight out of the 1990s.”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library” “all the UI elements look extremely unpolished to me”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library” “to me it's extremely ugly”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library” Verbose, reinvents existing tools
“ridiculously verbose their library is compared to React/Vue”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library” “looks like it's reinventing the wheels”
Comment from 3 Aug 2026 in “Bonsai: Janestreet's UI Library”
Other UI libraries people recommend
The two most recommended other UI libraries, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| Bonsai by Jane StreetThis page | 27 | 3 | 90% | 8 | 10 yrs3 owners | Approved |
| MicroUI by rxi | 13 | 2 | 87% | 2 | — | — |
| Reagent | 5 | 1 | 83% | 2 | — | — |
What people said
29 of the 33 comments that mention it, newest first. Each links to the original comment.
“it's so fast it feels like magic”
“It's written completely from scratch, and depends on nearly nothing external.”
“the engine looks really cool”
“That scale and view-distance..wow!! Brilliant work..”
“Wow, unbelievably cool. Good luck with the new game using the engine”
“Probably the most interesting thing about it at the moment is the editor.”
“is generally very functional for this purpose”
“agent based development works just fine, though probably a bit more token churn”
“long life to Bonsai - give me more, please!”
“The docs are a bit sparing but if you read the source its pretty cool to see how they did this.”
“ridiculously verbose their library is compared to React/Vue”
“all the UI elements look extremely unpolished to me”
“It focuses on utility and information density over design.”
“to me it's extremely ugly”
“Everything looks like it's straight out of the 1990s.”
“I was waiting for this to become possible!”
“looks like it's reinventing the wheels”
“I actually use it in my personal workflow these days to manage my contacts database!”
“For a success implementation, see Jane Street's Bonsai”
“Interesting project, but the slop readme made me quit reading halfway”
“Bonsai makes the vdom incremental and it is pretty fun to work with.”
“What a great idea to include tree sitter”
“definitely useful for non-C/Python languages”
“The bonsai framework with Elm inspired ocaml impl sounds v cool.”
“Bonsai reaches roughly 140 tokens/sec.”
“it appears that this person totally nailed it”
“the look and aesthetic of some of your screenshots is awesome”
“Strong plus is that you can render views of the finished room in Blender.”
“it's getting pretty close to being shadertoy for voxels”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.