A file hash is a fixed-length fingerprint calculated from file bytes. The same file gives the same hash, and a small file change produces a different hash.

SHA-256 is a SHA-2 family cryptographic hash algorithm that returns a 256-bit digest, usually shown as 64 hexadecimal characters.

Does HashCheck upload files?

No. HashCheck receives hash strings, not file contents.

FAQ

Practical answers about file hashes, SHA-256, online checking, adding hash records and integrating HashCheck into projects.

What Is A Hash?

A hash is a fixed-length digital fingerprint calculated from data. For files, the hash is calculated from the exact file bytes. If the file is unchanged, the same algorithm returns the same hash. If even one byte changes, the hash should change.

e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Hashes are used because they are compact, fast to compare and do not require sharing the original file. A hash is one-way: it is not a compressed copy of the file and cannot normally be converted back into the original file. Different files can theoretically collide, but strong modern hash algorithms make practical accidental collisions extremely unlikely.

What Is SHA-256?

SHA-256 is a cryptographic hash algorithm from the SHA-2 family. It produces a 256-bit result, usually displayed as 64 hexadecimal characters. It is widely supported and is generally preferred over older algorithms such as MD5 or SHA-1 for new integrations. HashCheck accepts common hex hash lengths, but SHA-256 is the recommended default for file checks.

Reference: NIST Secure Hash Standard.

How Do I Get A File Hash?

For project integration, use the ready examples on the Libraries page. For a one-time online check, calculate the hash locally when possible. Avoid uploading sensitive, private or illegal files to third-party online tools.

Built-in Commands

System	Command	Reference
Windows PowerShell	`Get-FileHash "C:\path\file.ext" -Algorithm SHA256`	Microsoft Get-FileHash
macOS Terminal	`shasum -a 256 /path/to/file`	shasum manual
Linux Terminal	`sha256sum /path/to/file`	GNU Coreutils

Online And Desktop Tools

CyberChef - browser-based hashing and data tools.
emn178 SHA-256 File Checksum - browser-based SHA-256 file checksum page.
OpenHashTab - desktop shell extension for file hashes.
7-Zip - desktop software that can calculate checksums through the file context menu or command line.

How Do I Check A Hash Online?

Calculate the file hash using a local command, desktop tool or trusted browser-local tool.
Copy the hash string, for example a 64-character SHA-256 value.
Open HashCheck.
Paste the hash into the online lookup box.
Click Check hashes.
Read the result code: 0 not found, 1 Xexle service list, 2 validator-submitted, 3 user-submitted.

How Do I Add A Hash Online?

Calculate the file hash first. Do not upload the file to HashCheck.
Open Add hashes.
Paste up to 3 valid hash strings.
Submit only hashes you have a lawful and good-faith reason to report.
Click Add hashes.
Wait 15 minutes before the next anonymous online submission.

How Do I Integrate HashCheck Into A Project?

Use the Libraries page for starter code in Python, Node.js, PHP, Go and Bash. The typical flow is: calculate SHA-256 locally, send only hash strings to /api/check, and handle lookup codes in your application. Validator API submissions require a validator token.

Does HashCheck Store My Files?

No. HashCheck stores hash strings and limited metadata. The public check and add flows do not upload file contents.

Does A Hash Match Prove A File Is Illegal?

No. A hash match is a technical signal. It may indicate an Xexle service record, trusted validator record or user-submitted report, depending on the returned code. Legal and moderation conclusions require proper review and source context.

Can I Check Many Files?

Yes. Use the API or code examples to calculate hashes locally and send them in batches. The public lookup limit is 1000 valid hashes per request.