Siril review: the free little brother of PixInsight
Where does it rank on our leaderboard
| Rank | Software | Stars for Your Buck | Recorded UK price |
|---|---|---|---|
| 1 | Stellarium | 100 out of 100 | Free |
| 2 | NINA | 98 out of 100 | Free |
| 4 | GraXpert | 96 out of 100 | Free |
| 8 | NoiseXTerminator | 92 out of 100 | £45 |
| 10 | Siril | 88 out of 100 | Free |
| 11 | StarXTerminator | 85 out of 100 | £45 |
| 13 | RegiStax | 77 out of 100 | Free |
| 15 | DeepSkyStacker | 71 out of 100 | Free |
| 16 | Adobe Photoshop | 67 out of 100 | £22 |
Contents
- 01 Where does it rank on our leaderboard
- 02 Specifications and features
- 03 A walk through Siril
- 04 Should you buy it?
- 05 Questions and more about this review
In 30 seconds
Stars for Your Buck 88/100
Written 2 Oct 2026 Updated 2 Oct 2026
- Rank
- #10 of 16 software
- Verdict
- Damon's pick
Written by Damon Scotting 3 min read
Buy it if
- You want many of PixInsight's processes without paying for them.
- You have outgrown DeepSkyStacker and want the next step up.
Skip it if
- You can justify PixInsight's hefty one-off price: it is still my own first choice of the three.
“Siril is the middle stage of the evolution. If DeepSkyStacker is Charmander and PixInsight is Charizard, Siril is Charmeleon: the free little brother of PixInsight, doing many of the same processes at no cost. PixInsight is still my own first choice of the three, but once you factor in its hefty one-off price, Siril is the better value by a distance. It is loved by amateur astrophotographers for good reason.”
Specifications and features
Against the software I have reviewed
Compare with
| Siril reviewed #10 of 16 | DeepSkyStacker #15 of 16 | PixInsight #14 of 16 | |
|---|---|---|---|
| Recorded UK price | Free | Free | £258 |
| Stars for Your Buck | 88/100 | 71/100 | 76/100 |
| Made by | The Siril team (free-astro) | Created by Luc Coiffier in 2006; open source since 2018 | Pleiades Astrophoto (Spain) |
| Price | Free | Free | not recorded |
| What it is for | Astronomical image processing, made for stacking many frames to raise the signal-to-noise ratio | Registering and stacking deep-sky frames | Processing astrophotographs |
| Current version | 1.4.4 (17 June 2026) | 6.2.2 (18 July 2026) | 1.9.4 Lockhart |
| Operating systems | Windows 64 bit, macOS (Intel and Apple silicon), Linux | Windows 10 or later (64 bit), macOS 13.4 or later, Linux | Windows 11, macOS 26 and 15, Linux |
| Mac requirement | macOS 13 Ventura or later | macOS 13.4 Ventura or later | not recorded |
| Memory | 8 GB recommended | not recorded | not recorded |
| Licence | Free and open source (GNU GPL v3) | Free and open source (BSD 3-Clause) | €300 outside the EU; 45-day free trial |
A walk through Siril
Image workspace My finished North America Nebula open in Siril's RGB view, the red, green and blue channels on their own tabs and the display controls along the bottom.
Background extraction The Background Extraction dialog: samples per line, smoothing and grid tolerance shape the background model, and the correction is set to subtraction.
Scripts The Scripts menu: Siril script files, Python scripts, Get Scripts and a script editor.
Should you buy it?
88/100 Stars for Your Buck
Pros
- The free little brother of PixInsight, doing many of the same processes at no cost.
- Once you factor in PixInsight's hefty one-off price, Siril is the better value by a distance.
- The middle stage of the evolution: the next step up from DeepSkyStacker.
Cons
- PixInsight is still my own first choice of the three.
It is loved by amateur astrophotographers for good reason.
Three alternatives I have reviewed
- PixInsight My own first choice of the three, at a hefty one-off price 76/100 £258 Read the review
- DeepSkyStacker Free, straightforward stacking: where the evolution starts 71/100 Free Read the review
- GraXpert Free gradient removal, deconvolution and noise reduction for a stacked image 96/100 Free Read the review
Questions and more about this review
Reviewed by
Damon Scotting
The Telescope Man Verified
BSc (Hons) Physics with Astrophysics and Cosmology, Loughborough University PGCE / QTS, University of Nottingham
About Damon About Damon Damon Scotting is The Telescope Man. He holds a BSc (Hons) in Physics with Astrophysics and Cosmology from Loughborough University and a PGCE with QTS from the University of Nottingham, and taught physics in secondary schools before becoming an astronomy creator. He is a contributing writer for BBC Sky at Night Magazine and the author of 42 Wonders of Our Night Sky, and his photograph of the galaxy M100 with the dwarf planet Ceres was Highly Commended in the Astronomy Photographer of the Year 2024 competition run by Royal Observatory Greenwich. He has appeared on the BBC's Blue Peter. More than 750,000 people follow his astronomy channels on YouTube, Instagram and TikTok, and he has reviewed more than 140 telescopes, mounts, cameras, filters and accessories hands-on for this site. More about Damon · How I test · Damon's book
I review all kinds of gear: most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way. How this site is funded
Five questions, answered
Questions about the Siril
Written 2 October 2026 ·Updated 2 October 2026
I review all kinds of gear. Most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way: no company sees or approves a review before it is published. How this site is funded
- Is Siril free? Yes. Siril is free and open source, under the GNU GPL version 3, with downloads for 64-bit Windows, macOS (Intel and Apple silicon) and Linux. The specifications and the comparison table ↓
- Which version is current? Siril 1.4.4, released on 17 June 2026. The specifications and the comparison table ↓
- Does Siril run on an older Mac? Siril's documentation asks for macOS 13 Ventura or later. The specifications and the comparison table ↓
- Should I choose Siril or PixInsight? PixInsight remains my own first choice, but Siril does many of the same processes for nothing, so for most people it is the better value. The specifications and the comparison table ↓
- What have I not tested on the Siril? My screenshots show Siril with my finished North America Nebula JPEG open; no background extraction, stacking or script was run for them.