What is ROT47 and how does it work?

ROT47 is a simple substitution cipher over the printable ASCII range, code points 33 to 126, which is ninety-four characters covering letters, digits and most punctuation. It rotates each of those characters forward by 47 places and wraps around at the end of the range. For example the letter H at code 72 maps to w, and the digit 0 at code 48 maps to an underscore. Because 47 is half of 94, applying ROT47 a second time lands you back where you started, so it is its own decoder. It is obfuscation, not encryption, since there is no key.

How is ROT47 different from ROT13?

ROT13 only rotates the twenty-six Latin letters A to Z and a to z, leaving digits, punctuation and spaces visible. ROT47 instead rotates the whole printable ASCII block, so 1, 2, 3 and symbols like the at sign or the slash also get scrambled. Take the string Order 42. With ROT13 the 42 stays readable, only the word Order changes. With ROT47 both the word and the number get rewritten, which is the point when you are hiding URLs, hashes or IDs that contain numbers and symbols.

Why is ROT47 self-inverse, so encoding equals decoding?

The visible ASCII alphabet that ROT47 operates on has exactly ninety-four characters. Shifting by 47 moves each character to the opposite side of that ninety-four wide ring. Shifting by another 47 completes a full loop of 94 and returns every character to its original spot, since 47 plus 47 equals 94. That is why there is a single button, not separate encode and decode modes. The same logic is why ROT13 uses 13, which is half of the twenty-six letter alphabet. Half the alphabet is always self-inverse.

What does the word Hello become under ROT47?

Hello becomes w6==@. Walk it through letter by letter. H is code 72, add 47 to get 119 which is w. The letter e is code 101, add 47, wrap past 126 and land on 6. Each l at code 108 maps to the equals sign, and o at code 111 maps to the at sign. So Hello turns into w6==@, and running ROT47 on w6==@ gives Hello straight back, which you can verify with the swap button in this tool.

Does ROT47 change numbers and punctuation, and what about spaces?

Yes. Digits 0 to 9 and punctuation marks all sit inside the printable ASCII range, so they are rotated just like letters. The digit 5 at code 53 becomes the letter d, and an exclamation mark at code 33 becomes a capital P. Spaces, tabs and newlines fall outside the 33 to 126 range, so they are kept exactly as they are, and any non-ASCII text such as Chinese characters or emoji is also left untouched so your line breaks and layout survive the transform.

Hide a spoiler or punchline in a forum post

ROT47 carries on the old Usenet habit of scrambling spoilers so a reader has to take a deliberate step to reveal them. Unlike ROT13, which leaves numbers and links readable, ROT47 also hides the episode number, the score or the URL inside your spoiler. Paste your reveal, copy the scrambled text into the thread, and add a note that readers can drop it back into this tool to read it.

Obfuscate a config string or token in a code comment

Sometimes you want a sample value in a code comment or a gist to be present but not instantly copy-pasteable, for example a placeholder API path or a demo ID. ROT47 rewrites the digits and symbols as well as letters, so the string stops looking like a live credential while staying trivially reversible by anyone who knows it is ROT47.

Solve or build CTF and puzzle challenges

ROT47 is a staple in capture-the-flag and escape-room style puzzles because it touches the whole printable ASCII set. When a flag looks like rotated gibberish full of symbols rather than just shifted letters, ROT47 is usually the answer. Drop the ciphertext in, read the flag, or run it the other way to author a fresh challenge.

Teach how substitution ciphers and modular arithmetic work

Because the output of ROT47 visibly changes digits and punctuation, it is a vivid classroom example of rotation over a fixed alphabet and of why a shift of half the alphabet is self-inverse. Students can type their name, watch every glyph move, then apply it again and see the original return, which makes the modular wrap-around concrete.

ROT47 Encoder and Decoder Online

Rotate all visible ASCII by 47. Digits and symbols change too, fully self-inverse, runs in your browser.

Runs locally
Category Encoding & Crypto
Best for Checking small payloads, tokens, hashes, and encoded values quickly.

ROT47

ROT47 shifts every printable ASCII character (codes 33 to 126) by 47, so digits and punctuation change too. It is self-inverse: the same action encodes and decodes.

Input0 chars

Output0 chars

ROT47 result appears here.

What this tool does

Free online ROT47 encoder and decoder that works entirely in your browser. ROT47 shifts every visible ASCII character (code points 33 to 126, ninety-four glyphs in total) by 47 positions. Unlike ROT13, which only touches the twenty-six Latin letters, ROT47 scrambles digits, brackets, slashes and punctuation as well, so a URL or an order number no longer leaks through in plain sight. Because 47 is exactly half of 94, the transform is its own inverse, meaning the same single action both encodes and decodes. Type or paste on the left and the result appears on the right as you type, with no submit button and no server round trip. Spaces, tabs, newlines and any non-ASCII text such as Chinese, Cyrillic or emoji pass straight through untouched. One click copies the output, and the shareable URL reproduces your exact input. Everything is plain client-side JavaScript, nothing is uploaded, and it loads in well under ten kilobytes.

Tool details

Input: Text; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Encoding & Crypto · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How ROT47 Encoder & Decoder fits into your work

Use it for quick browser-side encoding, decoding, hashing, token checks, and share-safe transformations.

Encoding jobs

Checking small payloads, tokens, hashes, and encoded values quickly.
Preparing values for APIs, URLs, docs, or support tickets.
Avoiding account-based tools when the input might be sensitive.

Encoding checks

Do not paste live secrets unless you are comfortable with local browser handling.
Confirm whether the operation is reversible before sharing the result.
For hashes, compare the exact algorithm and casing expected by the receiver.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Hide a spoiler or punchline in a forum post
ROT47 carries on the old Usenet habit of scrambling spoilers so a reader has to take a deliberate step to reveal them. Unlike ROT13, which leaves numbers and links readable, ROT47 also hides the episode number, the score or the URL inside your spoiler. Paste your reveal, copy the scrambled text into the thread, and add a note that readers can drop it back into this tool to read it.
Obfuscate a config string or token in a code comment
Sometimes you want a sample value in a code comment or a gist to be present but not instantly copy-pasteable, for example a placeholder API path or a demo ID. ROT47 rewrites the digits and symbols as well as letters, so the string stops looking like a live credential while staying trivially reversible by anyone who knows it is ROT47.
Solve or build CTF and puzzle challenges
ROT47 is a staple in capture-the-flag and escape-room style puzzles because it touches the whole printable ASCII set. When a flag looks like rotated gibberish full of symbols rather than just shifted letters, ROT47 is usually the answer. Drop the ciphertext in, read the flag, or run it the other way to author a fresh challenge.
Teach how substitution ciphers and modular arithmetic work
Because the output of ROT47 visibly changes digits and punctuation, it is a vivid classroom example of rotation over a fixed alphabet and of why a shift of half the alphabet is self-inverse. Students can type their name, watch every glyph move, then apply it again and see the original return, which makes the modular wrap-around concrete.

Common pitfalls

Expecting ROT47 to keep numbers readable the way ROT13 does. ROT13 only touches letters, but ROT47 covers the whole printable ASCII set, so a code like 12345 becomes a string of symbols. If you wanted the digits left alone, you needed ROT13 or ROT18, not ROT47.
Thinking ROT47 is encryption and using it to protect a secret. There is no key, the mapping is fixed and public, so anyone can reverse it in one line of code. Use it for obfuscation and puzzles only, and reach for AES-GCM or age when you actually need confidentiality.
Pasting text with smart or curly quotes and wondering why they survive unchanged. Curly quotes are non-ASCII characters outside the 33 to 126 range, so ROT47 leaves them as they are. Convert them to straight ASCII quotes first if you want them scrambled along with the rest.

Privacy

Every ROT47 transform here is plain JavaScript running inside your browser tab. Your text never leaves the page and nothing is logged. The one caveat is that the shareable URL encodes your input in the query string, so a share link pasted into chat will record that text in the recipient server access log. For anything sensitive, use the copy button and paste the result rather than sharing the URL.

FAQ

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ROT47 Encoder and Decoder Online

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How ROT47 Encoder & Decoder fits into your work

Encoding jobs

Encoding checks

Good next steps

Real-world use cases

Hide a spoiler or punchline in a forum post

Obfuscate a config string or token in a code comment

Solve or build CTF and puzzle challenges

Teach how substitution ciphers and modular arithmetic work

Common pitfalls

Privacy

FAQ

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