Générateur de Somme de Contrôle de Fichier
MD5, SHA1, SHA256, SHA512 for uploaded files
100 % gratuit. Fonctionne entièrement dans votre navigateur : vos fichiers et données ne quittent jamais votre appareil et rien n'est envoyé à un serveur.
Click or drag a file here
Any file type supported
À propos de cet outil
A checksum is a fixed-length fingerprint computed from a file's contents, with one crucial property: changing a single bit produces a completely different result. That makes it a reliable way to answer "is this file exactly what it should be" - which matters after a download over an unreliable connection, and matters far more when the file is an installer or a disk image. Publishers list the expected checksum precisely so you can verify what arrived. Algorithm choice matters for the second case. MD5 and SHA-1 are both cryptographically broken: attackers can deliberately construct two different files with the same hash, so a matching MD5 no longer proves a file has not been tampered with. Both are still fine for detecting accidental corruption, which is a different question. For any verification where a malicious substitution is the concern, use SHA-256 - and prefer the checksum published on a different channel from the file itself. Hashing runs in your browser.
Comment utiliser cet outil
- Select your fileIt is read locally - large files are hashed in chunks so browser memory is not a limit.
- Pick the algorithmMatch whichever the publisher listed. SHA-256 is the right choice when you have one.
- Compare with the published valueThey must match exactly and completely. A partial match means nothing.
- Treat a mismatch as a failureDo not run the file. Re-download it, and if it still differs, be suspicious of the source.
Pourquoi l’utiliser
- Runs in your browser - files are never uploaded, which matters for anything confidential.
- Four algorithms, so you can match whatever the publisher provided.
- Handles large files by hashing in chunks rather than loading everything into memory.
- No file size limit imposed by a server.
- No account required.
Usages courants
- Verifying an ISO or installer download before running it.
- Confirming a large file transferred intact across a network or drive.
- Checking two files are identical without comparing them byte by byte.
- Recording a hash so you can prove a file has not changed later.
- Detecting silent corruption in a backup or archive.
Conseils pour de meilleurs résultats
- Use SHA-256 wherever the publisher offers it. MD5 and SHA-1 remain useful for corruption checks but not for tamper detection.
- Compare the whole string. Checking the first and last few characters is exactly what an attacker constructing a collision would rely on.
- Get the checksum from a different source than the file - a checksum hosted next to a compromised download is worthless.
- A mismatch is a stop signal, not a warning. Do not run the file.
- For verifying authenticity rather than integrity, a signature such as GPG is stronger than any checksum.
Erreurs à éviter
- Treating a matching MD5 as proof a file is safe. MD5 collisions can be deliberately constructed.
- Comparing only the start and end of the hash rather than the whole value.
- Downloading the checksum from the same compromised page as the file.
- Running an installer anyway after a mismatch, assuming the download was merely flaky.
- Confusing a checksum with encryption or a signature - it proves sameness, not secrecy or origin.
Questions fréquentes
Many software publishers provide the expected checksum alongside a download - comparing it against the checksum of your actual downloaded file confirms it wasn't corrupted during download or tampered with by a compromised mirror/server.
No - the checksum is computed directly in your browser; the file itself isn't uploaded anywhere.
Whichever the publisher listed, so you have something to compare against. Given a free choice, SHA-256 - it is the current standard and the only one of the four with meaningful collision resistance.
For detecting accidental corruption, yes. For proving a file has not been tampered with, no - MD5 collisions can be deliberately constructed, so a matching MD5 does not rule out a substituted file. SHA-1 has the same problem.
Do not run the file. Re-download it, since the usual cause is an interrupted or corrupted transfer. If it still differs after a clean download, treat the source as untrustworthy rather than assuming another glitch.
Yes. Files are read and hashed in chunks rather than loaded whole into memory, so multi-gigabyte ISOs work - they just take proportionally longer, since the work happens on your device.
Yes. File Checksum Generator is free for normal use with no account required, and ToolBox does not add a watermark to your result.
Most tools in this category run in your browser so the file stays on your device. If a tool needs a temporary server job, files are handled for that job only and are not kept as a lasting archive.
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