Key takeaways
- Use SHA-256 for anything someone could tamper with; RFC 6151 says MD5 is unwise where collision resistance is required.
- Neither MD5 nor SHA-256 is fit for storing passwords; OWASP recommends Argon2id, scrypt, bcrypt or PBKDF2 with a unique salt.
- AyeTab, a free browser tool, computes MD5 and SHA-256 from the same text locally, without uploading the input.
In the MD5 vs SHA256 choice, pick SHA-256 for anything a person could tamper with, and keep MD5 only for quick, non-security checks inside systems you already trust. If your team just needs to compute either one by hand, the free AyeTab hash tool shows both from the same input, right in the browser.
The short version for busy teams
Founders and operators rarely pick a hash function from scratch. The question usually arrives sideways: a vendor asks which checksum to publish, an engineer proposes MD5 for deduplication, or a security review flags an old integration. The answer depends on one thing: does it matter if someone can craft two different inputs with the same hash?
If yes, MD5 is out. RFC 6151, the IETF's updated security note on MD5, says the published attacks against it make MD5 unwise wherever collision resistance is required. Microsoft's PowerShell documentation goes further and says MD5 and SHA-1 are no longer considered secure and should be used only for simple change validation.
Side by side
| MD5 | SHA-256 | |
|---|---|---|
| Output size | 128 bits, 32 hex characters | 256 bits, 64 hex characters |
| Collision resistance | Broken by published attacks | Part of SHA-2, which NIST tells SHA-1 users to move to |
| Standard | RFC 1321 | NIST FIPS 180-4 (SHA-2 family) |
| Fair uses today | Cache keys, spotting accidental changes | Release checksums, signatures, integrity checks |
| Password storage | No | No, use a slow salted algorithm |
The last row surprises people. Neither algorithm is right for passwords. OWASP's password storage guidance says fast hashes such as SHA-256 let attackers try guesses too quickly, and recommends Argon2id, scrypt, bcrypt or PBKDF2 with a unique salt per password.
Where the choice shows up in a company
Publishing downloads. If you ship an installer, a dataset or a firmware image, publish a SHA-256 checksum next to it. Customers can verify the file with sha256sum on Linux or Get-FileHash on Windows, where SHA256 is the default algorithm.
Vendor questionnaires. Security reviews often ask how data integrity is checked. "SHA-256" is an answer reviewers accept; "MD5" invites follow-up questions.
Internal tooling. Deduplicating files in a pipeline you control, or naming cache entries, is where MD5 still shows up. It is fast and short. Even here, many teams standardize on SHA-256 so nobody has to remember which system used which.
Pseudonymizing data. Hashing an email address to use as an analytics ID is common. Be aware that short, guessable inputs can be found again by trying candidates, whichever algorithm you use.
Checking a value by hand
Engineers, support staff and analysts all end up comparing hashes now and then. A browser tool is the quickest way, but the input is often sensitive: a customer identifier, a token, a payload from production. Pasting that into an unknown website can send it to that site's server.
AyeTab runs the hashing inside the browser tab. Its Hash Generator returns MD5, SHA-1, SHA-256 and SHA-512 for text you type or paste, with no upload and no account, and it keeps working offline once the page has loaded. The same tools live in the free AyeTab Chrome extension, which puts them on the new tab page and in a side panel. For a team that wants one shared answer to "what is the hash of this", it is the first tool to hand out.
For large files, the command line is still the better route, because the browser page hashes text rather than file uploads.
Bottom line
Default to SHA-256. Treat MD5 as a legacy format you may still need to read, not one you choose for new work.
Frequently asked questions
Is MD5 still safe to use?
Only for non-security jobs such as cache keys or spotting accidental changes. Published collision attacks rule it out for signatures and tamper checks.
Is SHA-256 slower than MD5?
It does more work per byte, but for checksums and integrity checks the difference rarely matters. For passwords you actually want a deliberately slow algorithm, which neither is.
Can I convert an MD5 hash to SHA-256?
No. Both are one-way. You need the original input to compute its SHA-256.
