File Type Detector — Magic Bytes
Detect file types from hex bytes or base64 content by matching file signature (magic bytes).
How it works
- 1Paste or type your text in the input field
- 2Click "Detect" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About File Type Detector
File Type Detector is shaped around how people actually use web and productivity utility utilities online: open the page, drop in a file, get the result. Detect file types from hex bytes or base64 content by matching file signature (magic bytes). The interface stays out of the way once the work begins so the engine can use the available CPU and memory for the actual transformation.
The engine behind the page is standard browser APIs. It reads your file in-memory and writes the result back into the browser. For 0 MB and below the work usually completes in seconds; larger files mostly depend on how much spare RAM your device has.
File Type Detector fits naturally into the workflow of marketers running campaigns and analysts pulling lightweight reports, both of whom typically need a fast result inside the browser. There is no learning curve to budget for: anyone who has used a typical web upload form can complete a run on the first try.
The execution model is straightforward: your file is bytes in the tab's memory, the engine reads those bytes, computes the result, and hands the result back to the browser. The transformation happens locally, which is why the tool keeps working when your network connection drops mid-job and why it produces the same result every run for the same input.
File Type Detector is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
When the job finishes, File Type Detector hands you the result as a sensibly named file. Filenames are derived from your input where possible, so a quick batch of jobs leaves you with a tidy folder rather than a pile of generic "output (3)" files. Nothing is auto-saved on Favtoo's side because nothing was ever sent there.
The hard constraints are easy to remember. Maximum input: 0 MB. Multiple files per run: no — one input at a time, by design, to keep results predictable. The same controls apply on every run.
As a workflow component, File Type Detector is the part you reach for when a single, well-defined web and productivity utility step needs to happen. It performs that step and returns a standard file you can carry into the next part of your pipeline.
Some notes on the design of File Type Detector. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.
File Type Detector is one example of a broader pattern: utility software increasingly works as single-page, client-side experiences. Every page in the catalog is shaped that way, which keeps each tool fast to load and easy to recommend in a single link.
File Type Detector is built around the moment of need: a focused page you open when you have a specific task, complete the task, and close. The catalog contains many adjacent tools so the same model serves the surrounding parts of a typical web and productivity utility workflow.
Useful patterns when working with File Type Detector: keep the input file open in another tab so you can compare against the result; give the output file a descriptive name when saving so you can find it later (the default name is sensible but generic); and treat each run as independent — the tool has no concept of "history", which means you cannot accidentally pollute one job with leftovers from another.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
If File Type Detector solved your problem, sharing the page link with someone who has the same problem is the most useful thing you can do. The catalog grows mostly through word of mouth; visitors arriving through a recommendation tend to be the ones the tool serves best.
How it works
- 1Open File Type Detector in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Select the web utility file you want to process — drag-and-drop and the file picker both work.
- 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.
- 5Grab the output as soon as the run completes. You can also copy the result instead of downloading if the next tool in your workflow accepts pasted input.
- 6Repeat the process for additional inputs whenever you need to. The page stays loaded, so subsequent runs are quick.
Common use cases
- Generate a temporary asset for a social post using File Type Detector.
- Run a fast accessibility check before publishing.
- Compare two product variations side by side.
- Run a one-off check during a meeting without context-switching.
- Sanity-check a webhook response while debugging.
- Audit a marketing page before launch.
- Validate a setting before circulating it to a team.
- Preview how a result looks before deploying it.
- Plan content without paying for a SaaS dashboard.
FAQ
What are magic bytes?
The first few bytes of a file that identify its format — e.g., PNG starts with 89 50 4E 47.
How do I get hex bytes?
Use a hex editor, or run xxd or hexdump on a file. Paste the first 16+ bytes.
Base64 input?
Paste base64-encoded file content — the tool will decode and analyze the header bytes.
Which formats are detected?
PNG, JPEG, GIF, PDF, ZIP, GZIP, MP3, MP4, WOFF, EXE, ELF, and 30+ more formats.
Can it detect nested formats?
ZIP-based formats (DOCX, XLSX, JAR) share the ZIP signature — manual inspection may be needed.
Private?
Yes — detection runs locally.
Will File Type Detector keep working in a year?
File Type Detector 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 File Type Detector ask me to pay to download the result?
File Type Detector 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.
Why use File Type Detector instead of a paid online tool?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. File Type Detector sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common web and productivity utility operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Is File Type Detector mobile-friendly?
File Type Detector runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 0 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.
What permissions does File Type Detector need to function?
File Type Detector 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 long does Favtoo retain my data after using File Type Detector?
Favtoo keeps no copy of your file because Favtoo never receives your file. File Type Detector 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.
Does File Type Detector need an internet connection to run?
Once the page is loaded, File Type Detector 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 process multiple files at once with File Type Detector?
File Type Detector processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Can I use File Type Detector for commercial work?
File Type Detector can be used for personal and commercial work alike — there is no separate "business" licence to purchase. The output you generate is yours to use however you want, including in client deliverables, internal documents, or commercial products. Favtoo's only ask is fair, individual use; the tool is not designed to be embedded as a backend service or wrapped behind an API for resale.