FlowStorm review
A free, open-source debugger with recorded execution and backward navigation for Clojure teams.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
FlowStorm is an open-source debugger for Clojure and ClojureScript, designed for developers who need to understand program behavior across an entire recorded execution rather than inspect only the current pause point. It runs on Windows, macOS, and Linux, works independently of a specific IDE, and supports Clojure applications plus ClojureScript environments in browsers, Node.js, and React Native. Its free, open-source model makes it particularly suitable for teams and individual developers already working in the Clojure ecosystem.
The defining capability is omniscient debugging through execution recording. Developers can move forward and backward through code, navigate a recorded timeline, inspect call trees and functions, and review locals, arguments, return values, and stack information. Conditional thread breakpoints and exception-unwind inspection add control when investigating complex behavior. This approach can make historical state and execution flow more accessible than conventional pause-and-step debugging, especially when the issue depends on what happened earlier in a run.
FlowStorm also extends beyond local inspection. Remote debugging is available through nREPL and WebSocket connections, while a Clojure API supports programmable analysis of recordings. Custom data visualization and value inspection provide additional ways to examine application behavior. These capabilities suit interactive development workflows and teams that want to analyze recordings programmatically. Developers focused on languages other than Clojure or ClojureScript should choose a debugger aligned with their language stack. Likewise, projects needing only straightforward breakpoint debugging may prefer a simpler tool; FlowStorm is most compelling when recorded history, time travel, and deep inspection are central requirements.
FlowStorm pros and cons
- Where it wins
- Records execution for forward, backward, and time-based navigation
- Inspects call trees, locals, arguments, returns, stacks, and exceptions
- Supports remote debugging, programmable analysis, and custom visualization
- Where it doesn't
- Language coverage is focused on Clojure and ClojureScript
- Requires comfort with interactive development workflows
- Its feature set may exceed the needs of simple breakpoint debugging
FlowStorm fact sheet, pricing and score →
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