Milky Way stacking software for Mac, Windows & browsers

Compare platforms, files and scope.

These options cover different jobs. A fixed-tripod nightscape needs the moving sky aligned without dragging the stationary landscape along with it. Broader astronomy processing can involve calibration and registration before a separate landscape composite.

Documented capabilities checked October 11, 2026. Follow each developer's requirements for exact file and camera support.
Tool	Platform	Input & workflow	Useful distinction
Sequator	Windows; the official download lists Windows 10/11, 64-bit.	The manual recommends RAW and supports uncompressed 16-bit TIFF. Sky-region masking and 16-bit TIFF output are documented.	Includes foreground stacking in Freeze ground mode and options for lens or complex distortion. Our beta does not duplicate all of these functions.
Starry Landscape Stacker	Native Mac app.	Fixed-position nightscape sequences with identical exposure settings. Direct RAW support is documented from version 1.9 onward.	Offers multiple combination results, dark-frame subtraction and flat-field compensation, with manual mask refinement. The developer offers a trial and a Mac App Store purchase.
Siril	macOS, Windows and Linux; Mac downloads include Intel and Apple Silicon.	A broader astrophotography workflow. The manual covers raw-data conversion to FITS sequences, preprocessing and registration.	Registration with distortion correction is documented after an astrometry step. That workflow does not by itself establish an automatic sky-and-landscape composite.
Nightscape Stacker beta	Desktop Chrome or Edge; no app installation.	3–30 matching fixed-tripod JPEG, PNG or supported RGB TIFF files, up to 32 MP each. Camera RAW must be developed and exported first.	Manual sky mask, local alignment and averaging, one reference foreground, 16-bit sRGB TIFF export. Full TIFF export is currently free during beta.

“Browser” describes where the product runs. It does not mean that it handles every camera format, works entirely offline or produces a better image than a desktop tool.

Start with the task you need to finish.

A native Mac nightscape workflow

Consider Starry Landscape Stacker, especially if direct RAW input, calibration frames or multiple combination methods matter. Mac already has dedicated stacking tools.

A Windows sky-and-ground stack

Consider Sequator's documented sky-region and Freeze ground workflow. Read its distortion options if wide-angle corners are a recurring problem.

A broader astronomy data workflow

Consider Siril when you need sequence preparation, calibration or more control over registration. Plan the landscape-compositing step separately where your workflow needs it.

A first stack without another install

Try Nightscape Stacker when you can prepare compatible rendered files and accept a manual sky mask and a single reference foreground. Start with a small sequence before committing a whole evening's data.

There is no measured image-quality winner on this page. For your own comparison, use the same sequence, inspect the center and all four corners at 100%, then check the horizon and exported file.

Use the inspection and troubleshooting checklist →

When our browser beta is a fit.

The beta is designed for one modest task: align and average the sky in an untracked, fixed-tripod sequence while keeping the foreground from a chosen reference photo. Your photos are decoded and processed on your device, rather than uploaded for photo processing.

Bring matching files: 3–30 photos with the same framing, exposure settings and pixel dimensions, up to 32 MP each.
Use supported rendered RGB formats: JPEG, PNG or selected single-page, opaque sRGB TIFFs. TIFF support includes uncompressed and supported ZIP-compressed strip files; it is not universal TIFF support.
Mark the sky yourself: use the horizon tool, sky brush and eraser. This beta does not automatically separate fine branches.
Inspect before keeping: check stars at actual pixels and examine the downloaded TIFF in your editor.

Choose another workflow if you need direct camera RAW decoding, stacked or denoised ground, tracked skies, panoramas, mixed exposures, a separate blue-hour foreground, or automatic removal of moving clouds and trails. Severe lens distortion or weak star coverage can also make a sequence unsuitable for this beta.

Local photo processing still needs device memory and storage. The website and export access checks use a network connection; fully offline operation is not promised.

Try your sequence before planning a purchase.

Full-resolution 16-bit TIFF export is free during the public beta. General sales are not open yet. The planned browser Version 1 license is US$19.99 once, plus applicable tax.

Open the free browser stacker

Use the preparation advice for your chosen tool.

Do not transfer export settings blindly between stackers. Different programs expect different color spaces, file types and lens-preparation steps.

For example, our beta requires supported sRGB rendered files. Starry Landscape Stacker's own input-preparation instructions advise a different color-space workflow and warn against applying lens distortion correction before stacking in that product.

If you choose our beta, the Lightroom Classic export checklist explains its sRGB, 16-bit SDR TIFF settings, ZIP or no compression, matching dimensions and 32 MP limit. Those are compatibility choices for this product, not universal astrophotography settings.

Follow the full Lightroom → browser → TIFF tutorial →

Sources & related guides

Feature descriptions above come from the developers' documentation. Product support can change; check the linked instructions before preparing your full sequence.