JRuby
Hacker ApprovedThe most recommended of 4 Ruby implementations
Ruby running on the Java Virtual Machine, with access to Java libraries and full concurrency. Caveat: inline types are missed, and it is not quite identical to Ruby.
Ruby running on the Java Virtual Machine, with access to Java libraries and full concurrency. Caveat: inline types are missed, and it is not quite identical to Ruby.
15 people gave an opinion
- recommend it
- 13
- criticize it
- 2
- approval share
- 87%
Recommended in 9 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: not recommended
- March 2026: not recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: recommended
- July 2026: not recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 13 people recommend itNeeds 10 or more, met.
- 6.5 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 9 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
Runs Ruby on the JVM
“runs Ruby on a Java Virtual Machine with full concurrency and Ahead Of Time compilation”
Comment from 15 Sep 2026 in “Java 27” “I was surprised just how good JRuby was at working with all the same libraries as Java”
Comment from 5 Dec 2025 in “Minecraft creator's forgotten 2011 game, rewritten in TypeScript for the web” Viable alternative to MRI
“I love that Ruby has 3 high quality implementations in MRI, JRuby and Truffleruby.”
Comment from 14 Jan 2026 in “TruffleRuby 33 Is Released” “JRuby is way more viable than Jython ever was”
Comment from 21 May 2026 in “Saying Goodbye to Asm.js”
What people warn about
Each mark is one comment
Missing inline types
“although inline types are sorely missed still”
Comment from 22 Aug 2026 in “Kino: A high-performance Ractor web server for Ruby 4.0”
Other Ruby implementations people recommend
The three most recommended other Ruby implementations, 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 |
|---|---|---|---|---|---|---|
| JRubyThis page | 13 | 2 | 87% | 9 | — | Approved |
| Spinel Ruby compiler | 12 | 8 | 60% | 2 | — | — |
| TruffleRuby | 10 | 1 | 91% | 8 | — | Approved |
| mruby | 8 | 3 | 73% | 4 | — | — |
What people said
17 of the 18 comments that mention it, newest first. Each links to the original comment.
“the jvm implementations didn't help or actually actively hindered the effort to rein in memory usage”
“There is TruffleRuby and JRuby, which has been able to run Rails for a long time.”
“runs Ruby on a Java Virtual Machine with full concurrency and Ahead Of Time compilation”
“although inline types are sorely missed still”
“jRuby or TruffleRuby are better - and far faster - options”
“JRuby is way more viable than Jython ever was”
“it's almost ruby, but not really”
“JRuby and TruffleRuby were the real game changers”
“JRuby being a fairly well supported community project”
“For me jruby is a lot more accessible”
“I love that Ruby has 3 high quality implementations in MRI, JRuby and Truffleruby.”
“The one that always gets me is what Truffle/JRuby was capable of, ten years ago”
“enabled many of my cross-platform projects back in 201*”
“I wish JRuby gets more love”
“Sun toyed with JRuby, it was even officially supported on Netbeans”
“I was surprised just how good JRuby was at working with all the same libraries as Java”
“you can still use JRuby, and still leverage the language”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.