Metamath
Hacker ApprovedShares rank 5 of 8 proof assistants by recommenders
People recommend Metamath for its tiny, simple verifier kernel and the free book that teaches formal proofs. The most common caveat is that its tooling and interface feel archaic.
People recommend Metamath for its tiny, simple verifier kernel and the free book that teaches formal proofs. The most common caveat is that its tooling and interface feel archaic.
18 people gave an opinion
- recommend it
- 14
- criticize it
- 4
- approval share
- 78%
Recommended in 7 of 13 months
- November 2025: not recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: recommended
- March 2026: not recommended
- April 2026: recommended
- May 2026: not recommended
- June 2026: not recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 14 people recommend itNeeds 10 or more, met.
- 3.5 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 7 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
Tiny kernel, simple to implement
“metamath's design really speaks to me”
Comment from 4 Apr 2026 in “Automatic Textbook Formalization” “it's very simple, so much so that there are many implementations of checkers”
Comment from 27 Apr 2026 in “"Why not just use Lean?"” “Tiny checker kernel, no complicated dependent types, way less to go wrong.”
Comment from 5 Sep 2026 in “Formalizing Fermat's Last Theorem” - Comment from 1 Aug 2026 in “Postmortem for Kernel Soundness Bug #14576”
Free book explains how it works
“If one takes the time to read the free book accompanying the metamath software, and re implements it in about a weekend time, you learn to understand how it works internally.”
Comment from 13 Dec 2025 in “String theory inspires a brilliant, baffling new math proof” “If one takes the time to read the free book accompanying the metamath software”
Comment from 13 Dec 2025 in “String theory inspires a brilliant, baffling new math proof” “the website does a good job at introducing the system, while also offering a complete reference”
Comment from 9 Feb 2026 in “First Proof” Separate, trustworthy kernel and verifiers
“At least the metamath verifiers will not bend over backwards and come up with absurd inconsistent counterarguments.”
Comment from 3 Oct 2026 in “Treachery in the Rodin Museum 3D scan verdict” “seems to have a more trustable kernel wrt. the independent verifiers”
Comment from 2 Aug 2026 in “Postmortem for Kernel Soundness Bug #14576” “prover and verifier are essentially separate code bases”
Comment from 13 Dec 2025 in “String theory inspires a brilliant, baffling new math proof” Proofs hide nothing; transparent design
“In Metamath the proofs hide absolutely nothing.”
Comment from 30 Jul 2026 in “Are We Stuck with Lean?” “metamath's design really speaks to me”
Comment from 4 Apr 2026 in “Automatic Textbook Formalization”
Other proof assistants people recommend
The four most recommended other proof assistants, 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.
See all 8 proof assistants, rankedWhat people said
24 of the 25 comments that mention it, newest first. Each links to the original comment.
“At least the metamath verifiers will not bend over backwards and come up with absurd inconsistent counterarguments.”
“I consider Metamath a lot more lean than "Lean"”
“Tiny checker kernel, no complicated dependent types, way less to go wrong.”
“Everything else (Metamath, Mizar, AFP, Lean) is yet another ivory tower.”
“seems to have a more trustable kernel wrt. the independent verifiers”
“its kernel is so tiny that you can implement a verifier in a weekend”
“Took me about 90 seconds to find a Metamath implementation bug that apparently allowed proving something that shouldn't be provable”
“Stuff like this just wouldn't happen in Metamath.”
“Metamath is interesting for education in the principles of formal proofs”
“It looks like perl that has been written by someone who is in the process of having a stroke.”
“My favorite minimalistic example of the Metamath base language”
“In Metamath the proofs hide absolutely nothing.”
“You just changed one metalanguage for another.”
“it's very simple, so much so that there are many implementations of checkers”
“successful projects like metamath (us.metamath.org) where this exponential blow-up does not occur”
“its kernel design has a similar focus on simplicity while cleaning up a lot of metamath's cruft”
“metamath's design really speaks to me”
“the proof assistant and surrounding tooling is, archaic”
“Metamath0 in particular looks really intriguing”
“the website does a good job at introducing the system, while also offering a complete reference”
“If one takes the time to read the free book accompanying the metamath software, and re implements it in about a weekend time, you learn to understand how it works internally.”
“If one takes the time to read the free book accompanying the metamath software, and re implements it in about a weekend time”
“If one takes the time to read the free book accompanying the metamath software”
“prover and verifier are essentially separate code bases”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.