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FlowStorm

flow-storm.org

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Spec score 8.0 #8 of 27 in Debuggers

What it is

FlowStorm is a tracing debugger for Clojure and ClojureScript. It records execution without requiring breakpoints or code changes, then provides tools to step through code, inspect values, explore calls and functions, and investigate exceptions. A timeline displays execution events so users can follow how instructions from different threads interleave. The debugger also supports customizable real-time visualizations and plugins for specialized ways to examine recordings. Values shown in its interface can be sent to the REPL with one click, and recordings can be analyzed using Clojure. The guide covers ClojureScript in browsers, Node.js, and React Native, as well as remote debugging configurations and integrations for Emacs through Cider Storm, VS Code, and IntelliJ IDEA. FlowStorm is free and open source at free, and is listed for Linux, macOS, Windows, and self-hosted use. Minimum requirements are JDK 17 or later and Clojure 1.10.0 or later. Vanilla FlowStorm does not support async/await introduced in ClojureScript 1.12.145; the guide points to ClojureScriptStorm as an alternative.

Spec sheet

What it does
FlowStorm is a tracing debugger for Clojure and ClojureScript.Read 3 Oct 2026 · flow-storm.github.io
Integrations
The guide describes an Emacs front end called Cider Storm and setup instructions for VS Code and IntelliJ IDEA.Read 3 Oct 2026 · flow-storm.github.io
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.Read 3 Oct 2026 · flow-storm.github.io
Interactive programming
Values shown in the UI can be sent to the REPL with one click, and recordings can be analyzed using Clojure.Read 3 Oct 2026 · flow-storm.org
Languages and runtimes
The guide documents Clojure and ClojureScript, including ClojureScript in browsers, Node.js, and React Native.Read 3 Oct 2026 · flow-storm.github.io
Maker attribution
The user guide is attributed to Juan Monetta.Read 3 Oct 2026 · flow-storm.github.io
Plugins
A plugin system lets users add specialized tools to visualize and interact with recordings.Read 3 Oct 2026 · flow-storm.org
Recording
It can record and debug code without adding breakpoints or modifying the code.Read 3 Oct 2026 · flow-storm.org
Remote debugging
The guide documents remote debugging, including SSH tunnel, out-of-process, Docker, and React Native setups.Read 3 Oct 2026 · flow-storm.github.io
Requirements
The guide lists JDK 17 or later and Clojure 1.10.0 or later as minimum requirements.Read 3 Oct 2026 · flow-storm.github.io
Stepping and inspection
Its tools include code stepping, value inspection, call stack and function exploration, and exception debugging.Read 3 Oct 2026 · flow-storm.github.io
Threads
A timeline renders execution events to help users understand how thread instructions interleave.Read 3 Oct 2026 · flow-storm.org
Visualizations
It supports customizable and real-time data visualizations.Read 3 Oct 2026 · flow-storm.org

Plans and prices

Free and open source Free Free as in speech · no money involved · use it however you like Read 3 Oct 2026 · flow-storm.org

Every FlowStorm plan and price →

Strong points and limits

Strong points

  • Records execution without breakpoints or code changes.
  • Timeline shows interleaved thread events.
  • Send displayed values to the REPL with one click.
  • Supports plugins and customizable real-time visualizations.
  • Free and open source at free.

Limits

  • Requires JDK 17 or later.
  • Requires Clojure 1.10.0 or later.
  • Vanilla FlowStorm lacks support for specified ClojureScript async/await.

Who it suits

FlowStorm suits developers working in Clojure or ClojureScript who want to inspect recorded execution, including across threads. It also addresses users debugging browser, Node.js, or React Native ClojureScript applications.

Verdict

FlowStorm offers execution recording and inspection for Clojure and ClojureScript, alongside plugins, visualizations, and remote-debugging setups. Check the documented runtime requirements and the async/await limitation before choosing it for a ClojureScript project.

Where Specifiction places it

Alternatives to FlowStormAll alternatives →