Software · Education & science

Siril

Astronomical image processor.

Completely free
Windows and Linux
Open source

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Geographic availability: No geographic restriction found in our sources; availability is not checked country by country.

Technical details

Pricing: Completely freeconfirmed by Flathub
License: GPL-3.0+ — Open source (copyleft)confirmed by Flathub
Open source: Yes
Commercial use: Yesconfirmed by Flathub, Official plan pages (pricing, licence, terms)
Account required: not documented
Credit card required: Noconfirmed by Flathub
Watermark: Not applicable
Ads: not documented
Platforms: Windows and LinuxEstablished by Linux: Flathub · Windows: Winget
Publisher: Free-astro Team
Latest version: 1.4.4 (17 June 2026)
Latest activity: 19 June 2026

Overview

Features described in its Flathub listing: noise reduction.

Overview written by LicitPro from the documentation published by the authors and the cited sources; we have not tried the resource ourselves.

Excerpts that establish this information

“Siril is an image processing tool specially tailored for noise reduction and improving the signal/noise ratio of an image from multiple captures, as required in astronomy.” — Flathub, 10 November 2026

At a glance

Siril is completely free: it is open source software, and every feature is available without paying or subscribing.

Its licence (GPL-3.0+) is a copyleft open source licence: you may use, study, modify and redistribute it, including commercially; modified versions must keep the same licence.

Strengths

Open source code
Commercial use allowed

About

Siril is an image processing tool specially tailored for noise reduction and improving the signal/noise ratio of an image from multiple captures, as required in astronomy. Siril can align automatically or manually, stack and enhance pictures from various file formats, even images sequences (movies and SER files).

Description from Flathub — AppStream (Flathub)

Sources and checks

Facts collected from Flathub (credit card, publisher, licence, free status, platforms, commercial use, version) — 10 November 2026
Facts collected from Official plan pages (pricing, licence, terms) (commercial use) — 7 November 2026
Facts collected from Winget (Windows Package Manager) (publisher, platforms, version) — 6 November 2026
Last technical check: 6 November 2026
Description from Flathub — AppStream (Flathub)

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