SHA-1 Hash Generator

What is SHA-1?

SHA-1 (Secure Hash Algorithm 1) produces a 160-bit hash, shown as 40 hexadecimal characters. It was once the standard for digital signatures and certificates and is still used internally by systems such as Git to identify objects.

SHA-1 is now considered cryptographically broken — practical collision attacks exist — so it must not be used for new security work. Use it only for compatibility with existing systems, and choose SHA-256 for anything security-related.

Typical uses

• Reproduce or verify SHA-1 checksums from legacy software and APIs
• Inspect Git-style content hashes
• Compare integrity values when migrating off SHA-1

Runs locally

The hash is computed in your browser with the Web Crypto API. Your input never leaves the page.

Key features at a glance

• Produces a 160-bit SHA-1 hash as 40 hexadecimal characters
• Uses the browser's native Web Crypto API
• Hashes live as you type, with full UTF-8 support
• Optional uppercase output and one-click copy
• Ideal for reproducing legacy checksums and Git-style object IDs
• Runs entirely in your browser; input never leaves the page

Why SHA-1 still appears despite being broken

SHA-1 was the workhorse hash of the web for nearly two decades, used in TLS certificates, signatures, and countless protocols. Even though it is now cryptographically broken for collision resistance, an enormous amount of existing software was built around it, and that software does not disappear overnight. You still encounter SHA-1 in older APIs, legacy checksums, and internal identifiers that predate the move to SHA-2.

The most prominent example is Git, which uses SHA-1 to name every commit, file, and tree object. Git's use is about content addressing rather than defending against a malicious collision, so it has continued even as the wider world migrated away. Being able to compute a SHA-1 hash on demand remains useful precisely because so many systems still speak it for compatibility reasons.

What a broken hash means in practice

When cryptographers say SHA-1 is broken, they mean researchers demonstrated a practical collision: two distinct inputs that produce the identical hash, created on purpose. The landmark SHAttered attack in 2017 produced two different PDF files with the same SHA-1, proving the danger was real rather than theoretical. Once that is possible, an attacker can craft a benign-looking document and a malicious one that share a hash, defeating any signature that trusts the hash to be unique.

Crucially, this does not mean SHA-1 leaks its input or that every SHA-1 value is suddenly unsafe to compute. It means SHA-1 can no longer be trusted where an adversary controls the input and a collision would cause harm. For verifying non-adversarial legacy data it is still fine; for anything new and security-relevant, use SHA-256.

Tips for using SHA-1

• Use SHA-1 only for compatibility with existing systems, never for new security work
• Reach for SHA-256 whenever an attacker could influence the input
• Use it to inspect or reproduce Git-style content hashes
• Compare full digests when verifying legacy checksums
• Plan a migration path off SHA-1 for any security-relevant use you find

Why choose our SHA-1 hash generator?

Our generator is completely free with no signup, no limits, and no subscription. The hash is computed in your browser with the Web Crypto API, so your input never leaves the page and the tool keeps working offline — a real benefit when you are checking sensitive values.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you keep the tools you use most in a single dashboard. Alongside the MD5, SHA-256, and hash comparison tools, it rounds out a complete checksum toolkit that lives one click away.

Common use cases

Developers use the generator to reproduce or verify SHA-1 checksums from legacy software and APIs that have not migrated to SHA-2, and to inspect Git-style content hashes when debugging repositories or build systems. It is also handy when comparing integrity values during a migration off SHA-1.

Support and integration engineers use it to match the hash format an older partner system expects, confirming that both sides compute the same value for a given input. Because the result is deterministic, it provides a reliable point of comparison when tracking down why two systems disagree about a file or record.

Is the SHA-1 hash generator free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Hash as much text as you like at no cost.

Is SHA-1 safe to use today?

Not for security. Practical collision attacks exist, so SHA-1 must not be used for signatures, certificates, or anything an attacker can influence. It is acceptable only for compatibility with existing non-adversarial systems.

Why does Git still use SHA-1?

Git uses SHA-1 to address content — naming commits and objects — rather than to defend against malicious collisions. That use is largely unaffected by the attacks, and Git has added collision detection, so it continues for compatibility while gradually adding SHA-256 support.

Can a SHA-1 hash be reversed?

No. Like all hashes it is one-way. Tools that claim to reverse SHA-1 simply look up precomputed hashes of common inputs; they cannot recover arbitrary original text.

How long is a SHA-1 hash?

A SHA-1 hash is 160 bits, displayed as 40 hexadecimal characters, regardless of the input length. That is longer than MD5's 32 characters but shorter than SHA-256's 64.

What is the difference between SHA-1 and SHA-256?

SHA-1 produces a 160-bit (40-character) hash and is cryptographically broken, while SHA-256 produces a 256-bit (64-character) hash with no known practical collision attack. Use SHA-1 only for legacy compatibility and SHA-256 for anything security-related.

Is my input kept private?

Yes. Hashing runs locally in your browser via the Web Crypto API, so nothing you enter is uploaded. The tool is private and works without an internet connection.

How do I generate a SHA-1 hash from text?

Type or paste your text and the tool instantly computes its 40-character SHA-1 hash, updating as you type. Copy the result in one click — useful for checksums and legacy systems, though SHA-256 is recommended for new security-sensitive work.

Does the SHA-1 hash generator work offline?

Yes. The hash is computed entirely in your browser, so once the page has loaded the tool works without an internet connection, and your text is never uploaded. You can hash input privately on your own device.