Is DeepSkyStacker free?

Yes. It is free and open source, under the BSD 3-Clause licence.

Which computers does it run on?

DeepSkyStacker 6.2.2 supports 64-bit Windows 10 and later, macOS 13.4 Ventura and later (Apple silicon and Intel), and Linux.

Which frames can I give it?

Light frames, plus darks, flats, dark flats and offset (bias) frames, each opened from its own line of the main menu.

What have I not tested on the DeepSkyStacker?

No frames were loaded or stacked for my own screenshots; the loaded frames and the stacked galaxy in the walk-through come from the DeepSkyStacker website.

DeepSkyStacker review: free stacking and pure nostalgia

Where does it rank on our leaderboard

Nine of the 16 software on my board, against price
Rank	Software	Stars for Your Buck	Recorded UK price
1	Stellarium	100 out of 100	Free
2	NINA	98 out of 100	Free
5	BlurXTerminator	95 out of 100	£75
8	NoiseXTerminator	92 out of 100	£45
10	Siril	88 out of 100	Free
11	StarXTerminator	85 out of 100	£45
12	ASIStudio	82 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 DeepSkyStacker
04 Should you buy it?
05 Questions and more about this review

In 30 seconds

Stars for Your Buck 71/100

Written 2 Oct 2026 Updated 2 Oct 2026

Rank: #15 of 16 software
Verdict: Worth a look

Written by Damon Scotting 4 min read

Buy it if

You are starting out and want a free, straightforward stacker.
You want to learn what bias frames, darks and flats do for an image.

Skip it if

You want the best results today's tools can give: it has fallen well behind them.

“DeepSkyStacker is pure nostalgia for me. When I got into the hobby over ten years ago it was practically the only tool anyone recommended, and with good reason: it was free and it was straightforward. It was also the program that made me learn the technical side of astrophotography, from bias frames to darks and flats and how much they improve an image. It had an oddly early-internet feel. You would wait ages for a stack to finish, and then the image would appear block by block, and even a levels adjustment would redraw block by block. It made every result feel like a grand reveal. You would load your frames, make a cup of tea and wait thirty or forty minutes, and it felt more personal for it. It has fallen well behind the tools available today, and 71 may be generous, but it is hard to mark down something that costs nothing. Mathematically, its value is infinite.”

DSS Free

Specifications and features

Against the software I have reviewed

Compare with

DeepSkyStacker reviewed #15 of 16	Siril #10 of 16	PixInsight #14 of 16	ASIStudio #12 of 16
Recorded UK price	Free	Free	£258	Free
Stars for Your Buck	71/100	88/100	76/100	82/100
Made by	Created by Luc Coiffier in 2006; open source since 2018	The Siril team (free-astro)	Pleiades Astrophoto (Spain)	ZWO (Suzhou, China)
Price	Free	Free	not recorded	not recorded
What it is for	Registering and stacking deep-sky frames	Astronomical image processing, made for stacking many frames to raise the signal-to-noise ratio	Processing astrophotographs	Planetary and deep-sky capture, live stacking and stacking
Frames it takes	Light, dark, flat, dark flat and offset (bias)	not recorded	not recorded	not recorded
Current version	6.2.2 (18 July 2026)	1.4.4 (17 June 2026)	1.9.4 Lockhart	1.22
Operating systems	Windows 10 or later (64 bit), macOS 13.4 or later, Linux	Windows 64 bit, macOS (Intel and Apple silicon), Linux	Windows 11, macOS 26 and 15, Linux	Windows (64 and 32 bit), macOS, Linux
Mac requirement	macOS 13.4 Ventura or later	macOS 13 Ventura or later	not recorded	not recorded
Licence	Free and open source (BSD 3-Clause)	Free and open source (GNU GPL v3)	€300 outside the EU; 45-day free trial	Free download

A walk through DeepSkyStacker

Registering and stacking The main window of DeepSkyStacker 6.2.2, empty: light, dark, flat, dark flat and bias frames open from the menu on the left, and the file list waits below.

Registration settings The Register Settings dialog: a star detection threshold, here left automatic, and an option to reduce noise with a median filter first.

Framing the result The Result tab of the stacking settings frames the stack by the reference frame, as a mosaic or as the intersection of all frames, with optional 2x or 3x drizzle.

Frames scored and counted Light, dark and bias frames loaded and registered, each light frame with a score and a star count, and a globular cluster in the preview. Image: DeepSkyStacker website.

The finished stack A stacked spiral galaxy in the processing view, with levels for each colour channel and the histogram beside them. Image: DeepSkyStacker website.

Stacking methods How the light frames are combined: average, median, kappa-sigma clipping and more, with per-channel background calibration chosen here. Image: DeepSkyStacker website.

Should you buy it?

71/100 Stars for Your Buck

Pros

It is free and it is straightforward.
It teaches you the technical side, from bias frames to darks and flats, and how much they improve an image.
It is hard to mark down something that costs nothing.

Cons

It has fallen well behind the tools available today.

Mathematically, its value is infinite.

Three alternatives I have reviewed

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

Four questions, answered

Questions about the DeepSkyStacker

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 DeepSkyStacker free? Yes. It is free and open source, under the BSD 3-Clause licence. The specifications and the comparison table ↓
Which computers does it run on? DeepSkyStacker 6.2.2 supports 64-bit Windows 10 and later, macOS 13.4 Ventura and later (Apple silicon and Intel), and Linux. The specifications and the comparison table ↓
Which frames can I give it? Light frames, plus darks, flats, dark flats and offset (bias) frames, each opened from its own line of the main menu. A walk through DeepSkyStacker ↓
What have I not tested on the DeepSkyStacker? No frames were loaded or stacked for my own screenshots; the loaded frames and the stacked galaxy in the walk-through come from the DeepSkyStacker website.