head to head · open source
monolog vs defmt
monolog has 21,402 GitHub stars, 1,920 forks, 3 open issues and last shipped 4 days ago. defmt has 1,241 stars, 135 forks, 117 open issues and last shipped 3 days ago. monolog leads on adoption by 1,625% (21,402 vs 1,241 stars). monolog is written in PHP under MIT; defmt is written in Rust under Apache-2.0. monolog has attracted 9% as many forks as stars, defmt 11%. defmt was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (logging), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| monolog | defmt | |
|---|---|---|
| GitHub stars | ★ 21K | ★ 1.2K |
| License | MIT | Apache-2.0 |
| Written in | PHP | Rust |
| Last push | 2026-11-01 | 2026-11-02 |
| Forks | ⑂ 1.9K | ⑂ 135 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick monolog if
- You weight community size — 21K stars and counting
- You want the MIT license terms
- Your stack matches PHP
- You value the larger contributor base for long-term maintenance
pick defmt if
- You want the defmt feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and defmt fits your workflow better
About monolog
Monolog Logging for PHP Note This is the documentation for Monolog 3.x , if you are using older releases see the documentation for Monolog 2.x or Monolog 1.x Monolog sends your logs to files, sockets, inboxes, databases and various web services. See the complete list of handlers below. Special handlers allow you to build advanced logging strategies. This library implements the PSR 3 interface that you can type hint against in your own libraries to keep a maximum of interoperability. You can also use it in your applications to make sure you can always use another compatible logger at a later time. As of 1.11.0…
read the full monolog overview →
About defmt
defmt defmt ("de format", short for "deferred formatting") is a highly efficient logging framework that targets resource constrained devices, like microcontrollers. For more details about the framework check the book at . Components This repository contains the following packages: MSRV The minimum supported Rust version is 1.76 (or Ferrocene 24.05) for the crates that cross compile to your microcontroller. The minimum supported Rust version is 1.83 for all host side crates. The defmt crates are tested against the latest stable Rust version and the MSRV. Developer Information Running Tests Tests are run using…
read the full defmt overview →
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Frequently asked questions
Is monolog or defmt more popular?
monolog has 21,402 GitHub stars and defmt has 1,241. monolog has the larger community by that measure.
Are monolog and defmt free?
Both are open source. monolog is licensed under MIT and defmt under Apache-2.0. Neither carries a licence fee.
What is the difference between monolog and defmt?
monolog is written in PHP and defmt in Rust. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, monolog or defmt?
Choose monolog if you want the larger community (21,402 stars) or its MIT licence terms. Choose defmt if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.