User Agent Parser
Parse User-Agent strings to identify browser, engine, operating system, and device type.
How it works
- 1Paste or type your text in the input field
- 2Click "Process" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About User Agent Parser
User Agent Parser is a self-contained developer utility workspace. Parse User-Agent strings to identify browser, engine, operating system, and device type. Open the page, get the result, close the tab — that is the entire workflow.
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.
User Agent Parser is a static page plus a client-side engine. The browser does the work; there is no separate backend in the loop for the actual processing. That architecture is why the tool starts immediately, why it does not depend on the load on a remote service, and why running multiple jobs in a row does not slow it down.
The heaviest users of User Agent Parser tend to be backend developers inspecting requests, frontend developers prepping fixtures and QA engineers writing repro cases. Each group brings slightly different expectations to the tool, but the same single-page architecture serves every one of them with the same response time.
The right moment to reach for User Agent Parser is when you have a focused developer utility job that fits inside a browser tab. Open the page, drop in the file or paste your input, choose the options that matter, and the tool returns the result.
The architecture imposes only the limits the browser itself imposes. The published 0 MB ceiling is conservative; most modern devices comfortably handle inputs up to that size, and the cap exists so the tool degrades gracefully on phones and budget laptops rather than running out of memory.
For multi-step jobs, User Agent Parser sits next to Accept Header Parser, HTTP Header Analyzer, and cURL to Code Converter. None of them depend on each other — you can use User Agent Parser on its own — but together they cover the common variations of the task this page exists to handle.
User Agent Parser keeps the control set focused. Every option on the page is there because a real workflow needs it, and the defaults aim at the most common case so a first-time user can get the right output without changing any settings.
The download is delivered as a clearly named file the moment processing completes — no email link, no "your result will be ready in 5 minutes" queue, no expiry timer. The file is generated in your browser and saved by your browser's normal download flow.
Some context on why User Agent Parser exists in this form: modern File APIs, high-performance JavaScript engines, and well-maintained open-source libraries now make it possible to perform developer utility work entirely in the browser. User Agent Parser is built on top of that capability, which is why a single page can host the full pipeline.
User Agent Parser produces deterministic output: the same input plus the same options always produces the same result. That predictability matters when the result has to match an upstream specification or be reproducible later.
A few practical tips that experienced users of User Agent Parser pick up over time. First, keep your default browser updated — the engine relies on standard web APIs and newer browser versions are noticeably faster than ones from a few years ago. Second, close other heavy tabs before processing a large input; the engine shares CPU and memory with whatever else is open. Third, if you re-run the same kind of job often, your last-used settings are remembered for the rest of the tab session, so subsequent runs are essentially one click.
When something goes wrong, the cause is usually one of three things: a malformed input, a browser that is out of memory, or a corporate proxy that is interfering with the page's static assets. The first two are easy to diagnose; the third typically requires asking your IT team to allow standard browser APIs to load.
User Agent Parser is one of many single-purpose tools in the catalog. Each is built around the same single-page model. Use this one, close the tab, and come back the next time you need the same job done. None of the tools require prior knowledge of the others — each page is self-contained.
How it works
- 1Open the User Agent Parser workspace above. The interface is a single page, so there is nothing to navigate.
- 2Drop a developer file onto the upload area, or click to pick one from your device.
- 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.
- 4Trigger processing. standard browser APIs reads your input, applies the transformation, and writes the result back into the page.
- 5Download the result. The file is generated in your browser and saved through your normal download flow.
- 6Run additional jobs as needed. The same controls and defaults apply on every run.
Common use cases
- Pretty-print a minified blob during incident triage using User Agent Parser.
- Inspect a payload during local development without writing a script.
- Validate a config blob before pushing to staging.
- Generate a quick fixture without leaving the browser.
- Convert between data formats while wiring up an integration.
- Format a noisy log line into something a teammate can read.
- Hash a string for a quick reproducibility check.
- Decode a token to confirm its claims during a debugging session.
- Generate boilerplate from a single specification line.
- Compare two API responses to spot a regression.
FAQ
Which browsers are detected?
Chrome, Firefox, Safari, Edge, Opera, Vivaldi, Yandex, Samsung Internet, Chromium, and Internet Explorer.
Which OS is detected?
Windows (with version), macOS, iOS, Android, Linux distributions, and Chrome OS.
Does it detect bots?
Yes — common crawlers like Googlebot, Bingbot, Yandex, and Baidu are identified as Bot/Crawler.
What rendering engines?
Blink (Chrome/Edge), WebKit (Safari), Gecko (Firefox), and Trident (IE) are identified.
Where do I find my User-Agent?
Check browser DevTools console: navigator.userAgent. Or use your browser's request headers in the Network tab.
Private?
Yes — parsing runs locally using regex patterns.
Will User Agent Parser keep working if my Wi-Fi drops mid-task?
Once the page is loaded, User Agent Parser 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.
Does User Agent Parser work on a phone or tablet?
User Agent Parser 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.
Why is my browser prompting me when I open User Agent Parser?
User Agent Parser 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.
Is the source for User Agent Parser available?
User Agent Parser is a static page running an open-source engine in your browser, so a typical corporate firewall does not get in the way as long as it allows JavaScript to load from Favtoo. For teams that need to host it themselves on an internal network, the underlying engine (standard browser APIs) is open-source and can be packaged into a private build with the same behaviour. Reach out via the Contact page if that is something you are exploring.
What should I do if User Agent Parser fails on my file?
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is in a supported format and that it is below 0 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Can I process multiple files at once with User Agent Parser?
User Agent Parser 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.
Does User Agent Parser match what professional tools produce?
User Agent Parser is built on standard browser APIs, which is the same class of engine used by professional developer utility pipelines. For deterministic operations, the output is byte-identical to what an equivalent CLI run would produce; for operations involving a codec or a model, the result is well within the range of what comparable tools generate. If you have a specific reference output you need to match, run a small test job first to confirm the configuration produces what you expect.
Will User Agent Parser ask me to pay to download the result?
User Agent Parser 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.
Do I need a specific browser to use User Agent Parser?
User Agent Parser 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.