This page's audience our own tag's counts — open to see them

Period

–Visits

–Page views

–Clicks to vendors

–Time on page

–Reading now

Clicks to vendors, by tool

Top countries

Devices

– · visits, page views and clicks counted by our own tag, which counts more than our checked analytics; every figure rounded down · how we count

Fantomas

Free#21 of 34 in Code Formatting Tools

Fantomas: A focused open-source formatter for F# projects across .NET editors and CI workflows. Ranked #21 of 34 in Code Formatting Tools by our editors (7.2/10); pricing: Open source; best for F# developers using .NET IDEs.

7.2/10Editor score

Visit Fantomas

Fantomas7.2 Visit Fantomas

At a glance

Editor score
7.2 / 10
Pricing
Open source
Best for
F# developers using .NET IDEs
Paid from
Free
Supported languages
F#
Facts checked
21 Sep 2026

Where it wins
- Formats F# files and folders with .editorconfig configuration
- Checks formatting without changing files for CI workflows
- Supports editors, JSON output, ignore rules, and a library API
Where it doesn't
- Focused on F# rather than multi-language formatting
- Platform coverage is limited to web and self-hosted use
- Editor support depends on the listed integrations

Our verdict on Fantomas

Fantomas is an open-source formatter for F# source code, distributed as a .NET tool with an online formatter. It formats individual files or folders from the command line and supports configuration through .editorconfig. Developers working in F# projects can also check formatting without writing changes, making it suitable for CI workflows and style enforcement. Its focus is particularly relevant to teams using .NET-based development environments and F# codebases that need repeatable formatting rules.

Its strongest fit is the combination of command-line, editor, and automation features. Fantomas integrates with Ionide, FSAutoComplete, Visual Studio, Visual Studio Code, and JetBrains Rider, while an LSP-like daemon supports editor tooling. JSON output is available for scripts and coding agents, and .fantomasignore files use gitignore syntax to exclude selected paths. These options give teams several ways to place formatting into local development and automated workflows without limiting the tool to a single editor.

Fantomas also extends beyond a standalone formatter through Fantomas.Core and the CodeFormatter API, allowing programmatic formatting. That makes it a practical choice for developers who need both an established command-line workflow and a library interface. The trade-off is its narrow language scope: projects that require formatting for languages other than F# will need a separate tool. Choose Fantomas when F# consistency, editor integration, configuration, and CI checking are the priority; choose an alternative when broad multi-language coverage is central.

Your product? Our editors can test Fantomas in depth and publish a review, labelled as paid · from $149/mo →

Fantomas pricing

Plans Open sourceFree Free to use — no paid tier required for the core job.

See plans on fsprojects.github.io

Fantomas fact sheet

Free plan	Not verified
Paid from	Free
Supported languages	F#
Supported platforms	web, self_hosted
Editor integration	Yes
Ignore files	Yes
Changed-lines formatting	Not verified
Library API	Yes
License model	Open_source
Deployment	Cloud, Self-hosted
Platforms	Web
Support	Community, Docs
Built for	Solo, Small business, Mid-market, Enterprise (editorial estimate)
Integrations	5 integrations: Ionide, FSAutoComplete, Visual Studio, Visual Studio Code, JetBrains Rider
Pricing	Open source
Website	fsprojects.github.io
Facts checked	21 Sep 2026

Fantomas integrations

Fantomas lists 5 integrations on its own site.

Ionide
FSAutoComplete
Visual Studio
Visual Studio Code
JetBrains Rider

Alternatives to Fantomas

See all Fantomas alternatives →

Used Fantomas? Be the first to review it

The editor score above is our own research. What this page doesn't have yet is a reader's view — what you used Fantomas for, what worked and what didn't. No stars are seeded and no review is paid for; an editor reads every one before it appears.

Write a reviewTwo minutes · verified accounts only · read by an editor before it appears

Reviews come only from verified accounts. Sign in or create an account first — your e-mail is never shown.

Title

Your review

0 characters · at least 80, up to 3,000

Pros (optional · one per line)

Cons (optional · one per line)

Your name (shown with your review)

Role (optional)

Company (optional)

How long have you used it?

I've used Fantomas myself and this is my honest opinion — nobody paid or asked me to write it.

Posted from your verified account. Reviews appear after an editor reads them, usually within two working days.

Featured on iTechGuides

Fantomas is listed in our Code Formatting Tools directory. Add the badge to your site — it links back to this page.

<a href="https://www.itechguides.com/products/fantomas/"><img src="https://www.itechguides.com/best/badge/fantomas.svg" alt="Featured on iTechGuides" width="230" height="46"></a>

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated 7 Oct 2026 · How we research and update