Your images never leave your device
Graviton compresses and converts images inside your browser, so no image is ever uploaded. Here is exactly what our server does receive, how long it keeps it, and how to check for yourself in your browser’s network tab.
How it works
The compressor comes to your images
Most online compressors upload your photo, process it on their servers and send it back. Graviton does all of the work in your browser instead.
- 1
The encoders come to you
When you open Graviton, your browser downloads open-source image encoders compiled to WebAssembly. They run inside the page, like the rest of it.
- 2
Your image is processed on your device
The image you drop is read from your disk and compressed by Web Workers on your own processor. It stays in your browser’s memory.
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The result is saved from your browser
The full-quality file stays inside the in-browser engine until your download is approved. Single downloads and batch ZIP files are then created in your browser and saved straight to your device. Nothing passes through a server.
| What happens | Typical upload-based compressor | Graviton |
|---|---|---|
| Where your image goes | Uploaded to the service’s servers | Stays on your device |
| Who handles the file | The service and its hosting providers | Only your browser |
| What you wait for | Upload, processing and download | Processing on your own processor |
| What the server keeps | Depends on the service’s policy | On Free, only today’s download count for your account, for at most 48 hours. On Pro, nothing. |
That matters most for the images you would least like to hand to a stranger: passport and exam photos, signatures, scanned IDs, contracts and family photos. You can shrink an exam photo to a portal’s limit or get a signature to 10–20 KB without sending it to another service first.
It also makes Graviton quick. With nothing to upload, most photos are done in about a second, and the encoders are the same open-source engines described in how Graviton keeps images sharp.
What we receive
Exactly what our server receives
Compressing needs no account and sends nothing. When you download, your browser sends only a one-way fingerprint of each image, so the download can be approved and, on Free, counted. This is the complete list of what we receive and keep.
| What | Example | Kept for |
|---|---|---|
| A one-way SHA-256 fingerprint of each image you download | 9f2c4e…d81a (64 characters) | Not stored |
| On Free only: how many images your account downloaded today | 2 | At most 48 hours (nothing is kept on Pro) |
| Your account, held by Clerk | Your sign-in email and your plan | Until you delete your account |
What the fingerprint is used for
The fingerprint is used only to approve each download and, on Free, to count it against your daily limit, which resets at midnight UTC. Graviton doesn’t store it. Your browser keeps a download pass for each image you downloaded on this device until midnight UTC, so downloading the same image again that day, on the same device and in any format or size, isn’t counted twice. On Free, the only thing stored is one number, your account’s download count for today, for at most 48 hours. Pro has no limit, so not even that number exists.
What is never sent
- The image, or any of its pixels
- Previews, thumbnails or the compressed result
- File names, sizes or formats
- EXIF, GPS or camera data
What is a one-way fingerprint?
A SHA-256 fingerprint is a 64-character code calculated from the bytes of a file. The same file always produces the same code, so it identifies an image without showing it. The calculation only works in one direction: the code can’t be turned back into the image and reveals nothing about what the picture shows.
Your account
Sign-in and subscriptions are handled by Clerk, and your account holds your email and your plan. On Free, Graviton itself keeps only today’s download count, for at most 48 hours; on Pro, it keeps nothing. Your account gives us no access to your images, and when you delete it, your Graviton data is deleted with it.
Verify it
Check it yourself
You don’t have to take our word for it. Every desktop browser can show you each request a page makes, and it takes about a minute. On any device, going offline works too.
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Open the Network tab
Press F12 in Chrome, Edge or Firefox (Cmd+Option+I on a Mac) and choose Network. In Safari, first turn on the developer features in Settings → Advanced.
- 2
Compress a large photo
Drop a photo of a few megabytes into Graviton, compress it and download it while you watch the list of requests.
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Look for the upload
You won’t find one. No request carries anything close to the size of your photo, and the image itself never appears in the list.
To see what Graviton does send, keep the list open and click Download. Compressing sends nothing. The download makes one short request to our server, and it holds a 64-character fingerprint for each image and nothing else about the image.
The other requests you will see are the page itself, the encoder files your browser downloads, sign-in, and page-view and performance analytics. None of them contain your image.
To check offline, add an image and compress it once, then turn off Wi-Fi, or turn on airplane mode on a phone. Changing its quality, size or crop keeps working, because it all happens on your device. Downloading needs the connection again, to approve the download.
Metadata
Location and camera data are removed
Photos often carry hidden EXIF data, such as GPS coordinates, the phone that took them and when. By default Graviton removes it from every photo you download, and you choose what, if anything, to keep.
GPS location removed
Phone photos often record where they were taken. Every photo you download is saved without GPS coordinates unless you choose to keep them, so sharing it doesn’t share the place.
Camera details removed
EXIF data such as the camera or phone model, lens, exposure settings and capture time is removed by default, along with XMP, IPTC and comments. Serial numbers and maker notes are never kept.
Colors converted to sRGB
Re-encoded images are converted to sRGB, the standard color space for screens, so they look the same in every browser and app.
When an image keeps its format and is already as good as it gets (smaller than any compressed version, already under your target size, or with nothing to change), Graviton hands back your original. It keeps its exact pixels and loses only its metadata.
To keep some details, open More options and pick them under Keep metadata: the date taken for a photo library, or your copyright for your work. Serial numbers, maker notes, thumbnails, XMP and IPTC are never kept. Remove metadata from photos opens with compression off, for when you only want the metadata gone, and every setting, explained lists what each choice keeps.
FAQ
Privacy questions
Are my images uploaded anywhere?
No. Graviton reads, compresses and saves your images inside your browser. Nothing is sent while you compress or preview. When you download, our servers receive only a one-way SHA-256 fingerprint of each image, so the download can be approved and, on Free, counted. Graviton stores none of it and never receives the image or its file name.
Why do I need an account to download if nothing is uploaded?
Compressing, converting and comparing before and after are free and unlimited without one. Because the work happens on your device, an account is the only way to keep the free daily downloads fair: 3 a day on Free, and no limit on Pro. The account gives us no access to your images.
Do you keep the fingerprint?
No. It is used only to approve the download and, on Free, count it. On Free, the only thing Graviton stores is a single number: how many images your account downloaded today, kept for at most 48 hours. No images, files or fingerprints are kept. Pro has no limit, so not even that number exists. Your browser keeps a download pass for each image until midnight UTC, so downloading it again that day on the same device doesn’t count twice.
Can anyone rebuild my image from the fingerprint?
No. A SHA-256 fingerprint is a one-way code calculated from the file’s bytes. It can’t be turned back into the image and reveals nothing about what the picture shows.
Does Graviton remove GPS location from photos?
Yes, by default, along with the rest of the EXIF, XMP and IPTC data. That includes a JPG, PNG or WebP Graviton hands back as your original because it was already as small as it could be: its pixels stay exactly the same and only the metadata goes. To keep the location, pick Location under Keep metadata in More options.
Can I keep the date or my copyright?
Yes. Under More options, Keep metadata can keep Date taken, Copyright (artist and copyright), Camera (make, model, lens and exposure settings) and Location in JPG, PNG and WebP files; AVIF and GIF can’t carry it yet. Serial numbers, maker notes, thumbnails, XMP and IPTC are always removed. Your choice is remembered on this device.
Tools for this
Tools people use for images they would rather not upload anywhere.
Compress your next photo without uploading it
Compress as many images as you like on your own device, no account needed. A free account lets you download 3 a day, with every feature included.
Compress an image