XOR Cipher — Encrypt & Decrypt
Encrypt and decrypt text using XOR cipher with a custom key — fully reversible.
How it works
- 1Type or paste in the plain text field
- 2Conversion happens instantly in your browser
- 3Copy the result with one click
What to do next
About XOR Cipher
XOR Cipher is part of a collection of single-purpose developer utility tools. Encrypt and decrypt text using XOR cipher with a custom key — fully reversible. Each tool is intentionally narrow — it does one thing well rather than offering many overlapping features — which makes the common path predictable and the result easy to verify before you download or copy it.
Technically, the work is done by standard browser APIs, loaded as part of the page. Inputs are recognised automatically and validated before the engine begins processing. Files up to 0 MB are supported per run; that ceiling keeps browser memory usage stable on a wide range of devices.
XOR Cipher performs the transformation entirely inside the JavaScript runtime. Your file lives in the tab's memory while the engine works on it; the result lives in the tab's memory until the browser triggers the download. Both are released when the tab closes, the way every browser tab releases its memory.
Typical users of XOR Cipher include frontend developers prepping fixtures, devops engineers crafting one-liners and QA engineers writing repro cases. The thread connecting all of them is the same: a focused developer utility task that fits cleanly into a browser tab and benefits from a tool with sensible defaults and minimal setup.
XOR Cipher works well as a bookmarked utility you reach for when you need it. The first visit shows you what the tool does; the second is when you realise it is a low-friction option for the task and worth keeping in your tab list.
The only practical limit is the 0 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.
As a workflow component, XOR Cipher is the part you reach for when a single, well-defined developer utility step needs to happen. It performs that step and returns a standard file you can carry into the next part of your pipeline.
The transformation in XOR Cipher is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
The output handed back by XOR Cipher is the output file. If you would prefer to keep the result in the browser instead of downloading it, you can copy it from the result panel and paste it directly into another tab — useful when the next tool in your workflow expects pasted text rather than a file.
Some background on the design choices behind XOR Cipher: every option you see on the page is there because a real workflow needs it, and every option that is not shown has been deliberately omitted to keep the common case fast. The bias is toward minimal-but-complete.
If you also use a command-line tool for xor cipher, XOR Cipher is a convenient alternative for the times you are on a different machine or helping someone who is not comfortable in a terminal. The output is a standard file in the format documented above.
If you want to get the most out of XOR Cipher, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.
If the result is not what you expected, the most common causes are easy to check. Confirm the input is under the 0 MB ceiling — files just above the cap fail silently because the engine refuses to allocate the buffer. Confirm the input is one of the supported formats. And if the page itself feels slow, try closing other heavy tabs to free up memory; the engine runs in your browser, so it competes for the same resources as everything else open.
XOR Cipher is intentionally narrow in scope so the common case is fast and the result is predictable. If you ever need a variation it does not cover, browse the rest of the catalog — there is a good chance an adjacent tool already exists, and switching between tools is just a matter of opening another tab.
How it works
- 1Reach the XOR Cipher page in your browser to begin.
- 2Add your developer input by dropping it onto the page or browsing for it.
- 3Pick any non-default settings you need. Most users leave the defaults alone for the first run and only revisit if the result needs tuning.
- 4Click to start the job. The engine (standard browser APIs) processes the input in the page; you can watch the progress indicator until it completes.
- 5Download the result. The file is generated in your browser and saved through your normal download flow.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Validate a config blob before pushing to staging using XOR Cipher.
- Generate boilerplate from a single specification line.
- Inspect a payload during local development without writing a script.
- Hash a string for a quick reproducibility check.
- Encode binary content for transport in a JSON body.
- Inspect a regex against a test string before committing it.
- Format a noisy log line into something a teammate can read.
- Compare two API responses to spot a regression.
FAQ
How does XOR cipher work?
Each character is XORed with the corresponding key character. The same operation encrypts and decrypts.
How do I provide the key?
Append ::key::yourkey to your input. Example: hello::key::secret
Is XOR encryption secure?
Only with a truly random key as long as the message (one-time pad). Short repeating keys are easily broken.
Is the output hex?
Yes — the encrypted output is hex-encoded for safe display and storage.
Can I decrypt by reversing?
Yes — paste the hex output with the same key in reverse mode to get the original text.
Is data sent to a server?
No — processing happens in your browser.
Does Favtoo keep a copy of files I process with XOR Cipher?
Favtoo keeps no copy of your file because Favtoo never receives your file. XOR Cipher runs entirely in your browser, the input is held only in your tab's memory, and closing the tab discards it. There is no opt-in cloud history, no "recent jobs" panel synced to an account, and no server-side retention to configure — the architecture simply has nowhere for your file to be stored.
What permissions does XOR Cipher need to function?
XOR Cipher only needs the standard web platform — file picker access for the inputs you choose to load, and optionally clipboard access if you copy the result rather than downloading it. There is no microphone, camera, geolocation or background-permission request, because none of those are needed for the work the tool does.
How do I know I am using the latest version of XOR Cipher?
XOR Cipher is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.
Will XOR Cipher ask me to pay to download the result?
XOR Cipher is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Does XOR Cipher work in Safari, Firefox, Chrome and Edge?
XOR Cipher works in any modern browser released in the last few years — Chrome, Edge, Firefox, Safari, Brave, Arc and the major Chromium derivatives are all supported. The underlying engine relies on widely-supported web APIs, so there is nothing exotic to install. If you are on a very old browser version and the tool fails to load, updating to the latest release of your preferred browser is the only fix needed.
Can I use XOR Cipher offline?
Once the page is loaded, XOR Cipher can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
Can I use XOR Cipher on documents that contain personal data?
Your file is processed inside your browser by standard browser APIs. The engine reads the file's bytes from your tab's memory, computes the result, and writes the result back into the tab. You can confirm what the page does by opening developer tools and watching the Network tab during a run — the requests you see are for the tool's static assets only.