File Integrity Checker
File Integrity Checker for Files and Whole Folders
A file integrity checker hashes a file with an algorithm like SHA-256 and compares the result with a known-good value: same hash, same file. Check a single file free online, or save a SHA-256 baseline for a whole folder and re-verify it after every backup, copy, or migration.
Free online check · SHA-256, SHA-1, MD5, CRC32 · Desktop app for Windows, macOS, Linux
Single file, free online
Upload one file up to 10 MB and get MD5, SHA-1, SHA-256, and CRC32 to compare with a published value.
Whole folders, built-in commands
Save a SHA-256 baseline for every file in a folder on Windows, macOS, or Linux, then re-check it later.
Manifests you can keep
FolderManifest saves the baseline as a manifest and reports changed, missing, and added files after a backup or move.
How a file integrity check works
Every integrity checker, from a one-line command to an enterprise agent, follows the same four steps. The hash is a fingerprint of the file's bytes: change one byte and the SHA-256 value changes completely, while renaming or moving the file leaves it the same.
- 1
Hash the files while you know they are good
Calculate a SHA-256 hash for each file right after a download, a finished project, or a verified backup. This is your baseline.
- 2
Store the baseline somewhere else
Keep the list of hashes outside the folder you are checking, so a bad disk or a careless edit cannot change both at once.
- 3
Re-hash and compare
Later, or after a copy or migration, hash the files again and compare each value with the baseline.
- 4
Act on every mismatch
A changed hash means the file content changed. Restore it from a good copy, or confirm the edit was intended and update the baseline.
Check file integrity with built-in commands
You do not need to install anything to check a folder. These commands save a SHA-256 baseline and verify it later. Change the paths to your own folder, and keep the baseline file outside the folder you are checking.
Windows (PowerShell): save a baseline
Get-ChildItem "D:\Photos" -Recurse -File | Get-FileHash -Algorithm SHA256 |
Select-Object Hash, Path | Export-Csv "$HOME\photos-baseline.csv" -NoTypeInformationHashes every file under D:\Photos and writes hash plus full path to a CSV in your user folder.
Windows (PowerShell): check against it
$old = Import-Csv "$HOME\photos-baseline.csv"
$new = Get-ChildItem "D:\Photos" -Recurse -File | Get-FileHash -Algorithm SHA256
Compare-Object $old $new -Property Hash, PathNo output means nothing changed. <= rows exist only in the baseline (changed or deleted); => rows are new or changed now.
macOS (Terminal)
find ~/Projects/Client -type f -exec shasum -a 256 {} + > ~/client-baseline.sha256
shasum -a 256 -c --quiet ~/client-baseline.sha256The first line saves the baseline; run the second line later. --quiet prints only files that FAILED or are missing.
Linux (Terminal)
find /data/archive -type f -exec sha256sum {} + > ~/archive-baseline.sha256
sha256sum -c --quiet ~/archive-baseline.sha256Same idea with sha256sum. Files added after the baseline are not reported, so compare file counts too.
One file on Windows (Command Prompt)
certutil -hashfile "C:\Downloads\installer.exe" SHA256Compare the printed value with the SHA-256 the publisher lists. Upper or lower case does not matter.
More detail: PowerShell Get-FileHash, sha256sum on Linux, and verifying file integrity on Windows.
Where command-line checks get painful
The commands above work, and for an occasional check they are all you need. The friction shows up when you check the same folders repeatedly. You have to remember where each baseline lives, rebuild it after intended edits, and read raw output. sha256sum and shasum also stay silent about files added since the baseline, so an extra file slips through unless you count files separately.
Moves are the other trap. Because the baseline stores full paths, copying a folder to a new drive makes every path differ even when every byte is identical. You have to rewrite paths or hash relative to the folder root before the comparison means anything.
FolderManifest does this as a desktop workflow. It hashes a folder tree with SHA-256, saves the manifest, and later reports which files changed, went missing, or were added. It can also compare two folders directly, so you can check that a copy matches the original before you delete anything. Hashing runs on your computer; your files are not uploaded.
Which file integrity checker fits your job?
"File integrity checker" covers two different products. Personal and small-team checkers verify that your files survived a download, backup, or migration. Enterprise file integrity monitoring (FIM) watches servers for security changes. FolderManifest is the first kind, not the second.
| Option | Runs on | Scope | Best for |
|---|---|---|---|
| FolderManifest checksum calculator | Browser | One file, up to 10 MB | Checking a small download against a published hash. |
| certutil / Get-FileHash / sha256sum / shasum | Built into Windows, macOS, Linux | Files and scripted folder baselines | Large files, and people comfortable keeping CSV or .sha256 lists. |
| FolderManifest desktop | Windows, macOS, Linux | Whole folder trees, saved manifests | Backups, migrations, archives, and folders you need to prove are unchanged. |
| Enterprise FIM (e.g. Tripwire, OSSEC, Wazuh) | Server agents | System files, settings, fleets of servers | Security teams with compliance requirements and a SIEM. |
Want the full manifest workflow? See how FolderManifest verifies file integrity →
Frequently Asked Questions
What is a file integrity checker?
A file integrity checker calculates a cryptographic hash, such as SHA-256, for a file and compares it with a known-good value. If the hashes match, the file is byte-for-byte unchanged. If they differ, the file was corrupted or modified. Folder-level checkers save a hash for every file as a baseline and re-check the whole set later.
Does Windows have a built-in file integrity checker?
Yes, for single files. certutil -hashfile file SHA256 in Command Prompt and Get-FileHash in PowerShell both calculate SHA-256. For a whole folder you can pipe Get-ChildItem -Recurse into Get-FileHash, export the result to CSV, and compare it later with Compare-Object. Note that sfc /scannow is different: it only checks Windows system files, not your own documents.
Can I check file integrity online?
For small files, yes. The free FolderManifest checksum calculator accepts one file up to 10 MB, computes MD5, SHA-1, SHA-256, and CRC32 in memory on our server, and discards the file without storing it. For confidential or large files, use the built-in commands on this page or the desktop app, which hash files on your own computer.
Which hash algorithm should a file integrity check use?
Use SHA-256 when you can. MD5 and CRC32 still catch accidental corruption, but MD5 collisions can be manufactured on purpose, so a matching MD5 is weak evidence against tampering. If a publisher only lists MD5, check MD5; otherwise prefer SHA-256.
Is FolderManifest a file integrity monitoring (FIM) tool like Tripwire or Wazuh?
No. Enterprise FIM tools run as agents on servers, watch system files and settings, and feed security alerts into a SIEM for compliance programs. FolderManifest is a desktop app for folders you own: it saves SHA-256 manifests, re-verifies them, compares folders, and watches folders for changes. If you need server-wide security monitoring, use a dedicated FIM product.
Do checksum commands notice files that were added or deleted?
Partly. sha256sum -c and shasum -c report files from the baseline that are missing or changed, but they ignore files added after the baseline was made. The PowerShell Compare-Object method shows additions too. FolderManifest reports changed, missing, and added files in one result.
What users say
A clearer folder story, from people who use it.
“FolderManifest makes it easy to organize folder structures and manage duplicate files while keeping everything safe and secure.”
Mehedy H.Research and operations“I can understand a project folder at a glance, review what changed, and keep the cleanup process clear for everyone involved.”
Tasmina Akter C.Project coordination“FolderManifest clearly displays project structures and contents, making it easy to understand where everything is at a glance and maintain consistency across teams.”
Zahirul I.Business partnerBusiness-partner reviewCheck whole folders without keeping hash lists by hand
FolderManifest saves a SHA-256 manifest of every file and shows exactly what changed, went missing, or was added since. Runs locally on Windows, macOS, and Linux.
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