Manifold
Hacker ApprovedGeometry library in Developer tools
Fast, watertight boolean engine for OpenSCAD and other CAD tools. Critics say its triangle-mesh basis limits serious CAD use.
14 people recommended Manifold in Hacker News comments, 4 had mixed feelings and 3 criticized it, November 2025 to October 2026.
Summary written by Claude from 31 comments. It was written before the November 2026 recount, and 28 of those comments still count.
21 people gave an opinion
- recommend it
- 14
- mixed feelings
- 4
- warn against or regret it
- 3
The record
Recommended in 10 of 12 months
In 15 different threads.
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: not recommended
- September 2026: not recommended
- October 2026: recommended
Why it carries the badge
- 14 people recommend itNeeds 10 or more, met.
- 4.7 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 10 of 12 monthsNeeds 4 or more, met.
- Recommended in 15 threadsNeeds 5 or more, met.
- The biggest thread supplies 14% of its recommendersNeeds half or less, met.
The same rules apply to every product, and the badge can’t be bought. Mixed feelings count toward neither side. How the badge works
What people say about it
Reasons grouped from a sample of 26 of the 33 opinions about it, picked in proportion to how many people recommend it, have mixed feelings and criticize it. Each mark is one comment in the sample. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Much faster boolean operations than CGAL
“Trivial operations are two orders of magnitude faster and complex ones every faster.”
Comment from 20 Dec 2025 in “OpenSCAD is kinda neat” “The Manifold renderer is so much faster than the old CGAL”
Comment from 11 Oct 2026 in “OpenSCAD the Programmers Solid 3D CAD Modeller” “It will make your models “render” 10x faster (or more”
Comment from 20 Dec 2025 in “OpenSCAD is kinda neat” - Comment from 20 Dec 2025 in “OpenSCAD is kinda neat”
- Comment from 19 Nov 2025 in “Blender 5.0”
Watertight results, handles self-intersecting meshes
“The geometry engine is Manifold, which guarantees watertight meshes from boolean operations.”
Comment from 27 Jan 2026 in “Parametric CAD in Rust” “Manifold backend also eliminates the need to avoid coincident faces.”
Comment from 20 Dec 2025 in “OpenSCAD is kinda neat” “our library can still handle epsilon-valid self-intersecting meshes, rather than just reporting an error”
Comment from 31 Jul 2026 in “Show HN: Formally verified 3D CSG: Trust 93 lines spec, not 1000 lines AI code” Embedded in Godot and Blender
“I spent a lot of time making elalish/manifold work in Godot Engine and it is now a method in Blender too.”
Comment from 28 Jul 2026 in “Show HN: Formally verified 3D CSG: Trust 93 lines spec, not 1000 lines AI code” “That's why I integrated manifold into godot engine for constructive solid geometry!”
Comment from 28 Jul 2026 in “Show HN: Formally verified 3D CSG: Trust 93 lines spec, not 1000 lines AI code”
What people warn about
Each mark is one comment
Limits for serious CAD and manufacturing
“Manifold is good for visualization, but to use it as an engine for manufacturing .. its limits will be hit.”
Comment from 27 Jan 2026 in “Parametric CAD in Rust”
What people recommend instead
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 | Mixed | Criticize | Approval | Months | Had for | Badge |
|---|---|---|---|---|---|---|---|
| ManifoldThis page | 14 | 4 | 3 | 82% | 10 | — | Approved |
| S2 Geometry | 5 | 1 | 2 | 71% | 3 | — | — |
What people said
26 of the 33 opinions about it, picked in proportion to the three counts, newest first. Each links to the original comment.
“The Manifold renderer is so much faster than the old CGAL”
“our library can still handle epsilon-valid self-intersecting meshes, rather than just reporting an error”
“That's why I integrated manifold into godot engine for constructive solid geometry!”
“I spent a lot of time making elalish/manifold work in Godot Engine and it is now a method in Blender too.”
“the inline aspect is mostly for testing, and it’s awesome there.”
“You can inline native type-safe JSON directly in Java with the manifold project.”
“good for manifold for atleast not playing with real money but rather points like this”
“same for core.async vs manifold”
“manifold got a lot of things right”
“much better fit for actual production code that you want to optimize”
“you get to have social status if you know what the truth is”
“Manifold is a popular play-money prediction market.”
“The manifold project provides true delegation”
“Manifold actually explicitly encourages insider trading, arguing that it leads to more accurate pricing.”
“I think I've succeeded and many CAD tools use manifold for geometric kernels on 3d boundary meshes.”
“Manifold is good for visualization, but to use it as an engine for manufacturing .. its limits will be hit.”
“The geometry engine is Manifold, which guarantees watertight meshes from boolean operations.”
“Manifold is impressive, lots of info here”
“Which avoids using the OpenSCAD language, but also means you can't use BOSL2.”
“Manifold backend also eliminates the need to avoid coincident faces.”
“Trivial operations are two orders of magnitude faster and complex ones every faster.”
“The Manifold backend is no joke, probably 100x faster.”
“set the backend to Manifold”
“It will make your models “render” 10x faster (or more”
“I would use Manifold library there as much as possible”
“it is MUCH faster than the default CGAL one”
Counts come from 1,791,911 Hacker News comments labeled by Claude, November 2025 to October 2026, with data through October 31, 2026. Counts updated 2 Nov 2026. How we count. Report a mistake.