Side by side
UDB vs Xdebug
Both stand on debuggers. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free trial ExtensionLinux
UDB combines recording-based replay with conventional debugging controls for Linux C and C++ work. Its platform and user-space limits matter, but the free trial provides a way to evaluate it before purchase.
Visit UDB
Free plan LinuxMacSelf-hosted+2
Xdebug combines step debugging with tracing, profiling, and code coverage for PHP projects. Direct debugger connections may be blocked by network or firewall conditions; Xdebug Cloud is described as a relay for those cases.
Visit XdebugThe facts
| UDB | Xdebug | |
|---|---|---|
| Free plan | A free trial | Yes |
| Open source | Not published | Not published |
| Runs on | Extension, Linux | Linux, Mac, Self-hosted, Web, Windows |
| Lowest paid plan | Land and Prove Program: $50,000, paid once | Pro: £200 a year |
| Plans published | 1 | 2 |
| Maker | Not published | Not published |
| Website | undo.io | xdebug.org |
| On debuggers | #21 of 27 | #17 of 27 |
UDB: what it does well
- Replays execution in forward and reverse directions
- Inspects variables and memory
- Compatible with GDB
- Offers several named IDE integrations
- Requires no build or kernel configuration changes
What to know first
- Engine does not support Windows or macOS
- Kernel-space code is not supported
- ARM support is opt-in
- Pricing is available on request
Xdebug: what it does well
- Free PHP extension.
- Step debugger supports interactive code inspection.
- Profiler outputs Cachegrind-compatible files.
- DBGp is supported by nearly every PHP IDE.
- Browser helper extensions are listed for major browsers.
What to know first
- Paid Pro costs £200 per year.
- Business costs £1,000 per year.
- Community support has low issue priority.