FlowStorm
FlowStorm is a tracing debugger for Clojure and ClojureScript.
What FlowStorm is
FlowStorm is a tracing debugger for Clojure and ClojureScript. It records execution without requiring breakpoints or code changes, then lets you step through code, inspect values, explore calls and functions, and investigate exceptions. A timeline shows execution events to help make interleaving between threads visible. You can build customizable, real-time visualizations, add specialized tools through plugins, send displayed values to the REPL with one click, and analyze recordings using Clojure. Its guide covers ClojureScript in browsers, Node.js, and React Native, plus remote debugging setups and connections for Emacs through Cider Storm, VS Code, and IntelliJ IDEA. FlowStorm is free and open source, with Linux, macOS, Windows, and self-hosted availability. The listed minimum requirements are JDK 17 and Clojure 1.10.0 or later. One ClojureScript caveat: vanilla FlowStorm does not support async/await introduced in ClojureScript 1.12.145; the guide points to ClojureScriptStorm as an alternative.
Good
- Records execution without breakpoints or code changes
- Timeline helps show how thread events interleave
- Custom visualizations and plugins for recordings
- Free and open source
- Supports remote debugging and editor integrations
Watch out
- Requires JDK 17 or later and Clojure 1.10.0 or later
- Vanilla version lacks support for specified ClojureScript async/await
Who it suits
FlowStorm suits Clojure and ClojureScript developers who want to inspect recorded execution, including code running in browsers, Node.js, or React Native. It may also fit developers who need remote debugging or editor integrations.
Verdict
FlowStorm offers a broad set of tracing and inspection tools for Clojure and ClojureScript, including timeline views, visualizations, plugins, and REPL interaction. Check its runtime requirements and the async/await limitation if that feature is part of your ClojureScript work.
Plans and prices
From FlowStorm's own pricing page, checked 3 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free and open source | Free | Free as in speech · no money involved · use it however you like |
The facts
Each one read from FlowStorm's own pages, with the date it was checked.
What it does
- ClojureScript limitation
- Vanilla FlowStorm does not currently support async/await introduced in ClojureScript 1.12.145; the guide points to ClojureScriptStorm as an alternative with support.checked 3 Oct 2026
- Integrations
- The guide describes an Emacs front end called Cider Storm and setup instructions for VS Code and IntelliJ IDEA.checked 3 Oct 2026
- Interactive programming
- Values shown in the UI can be sent to the REPL with one click, and recordings can be analyzed using Clojure.checked 3 Oct 2026
- Languages and runtimes
- The guide documents Clojure and ClojureScript, including ClojureScript in browsers, Node.js, and React Native.checked 3 Oct 2026
- Plugins
- A plugin system lets users add specialized tools to visualize and interact with recordings.checked 3 Oct 2026
- Recording
- It can record and debug code without adding breakpoints or modifying the code.checked 3 Oct 2026
- Remote debugging
- The guide documents remote debugging, including SSH tunnel, out-of-process, Docker, and React Native setups.checked 3 Oct 2026
- Requirements
- The guide lists JDK 17 or later and Clojure 1.10.0 or later as minimum requirements.checked 3 Oct 2026
- Stepping and inspection
- Its tools include code stepping, value inspection, call stack and function exploration, and exception debugging.checked 3 Oct 2026
- Threads
- A timeline renders execution events to help users understand how thread instructions interleave.checked 3 Oct 2026
- Visualizations
- It supports customizable and real-time data visualizations.checked 3 Oct 2026
- What it does
- FlowStorm is a tracing debugger for Clojure and ClojureScript.checked 3 Oct 2026
The company
- Maker attribution
- The user guide is attributed to Juan Monetta.checked 3 Oct 2026
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