robots.txt Tester & Validator
Parse and validate robots.txt files — check rules, sitemaps, crawl-delay, and test URL matching.
How it works
- 1Paste or type your text in the input field
- 2Click "Test" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About robots.txt Tester
robots.txt Tester is built for developer utility jobs that fit cleanly into a browser tab. Parse and validate robots.txt files — check rules, sitemaps, crawl-delay, and test URL matching. The processing runs in the page itself, which is why the controls update instantly when you change settings and why a freshly loaded page is ready to do real work the moment it becomes interactive.
robots.txt Tester is implemented on top of standard browser APIs. Inputs are read from the file picker or drop zone, decoded in the browser, processed, and re-encoded into the output format. Files up to 0 MB are well within the comfort zone of any modern browser.
The execution path is auditable from the page itself: open developer tools, switch to the Network tab, run a job. The requests you see are static-asset GETs for the engine and the page resources. The actual work is JavaScript code running against the bytes already in your tab's memory.
If you fit any of these descriptions, robots.txt Tester should slot cleanly into your workflow: students learning new languages; data analysts wrangling JSON; devops engineers crafting one-liners. The tool keeps the controls focused on what matters for each of these use cases.
The right moment to reach for robots.txt Tester 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 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.
If your task needs more than one step, chain robots.txt Tester with XML Sitemap Parser, Content Security Policy Tester, and RSS Feed Validator. Each tool produces output that is a clean input to the next, so multi-step workflows are just a matter of opening the next tool in a new tab and continuing.
robots.txt Tester is honest about scope: it handles a single, well-defined developer utility step. Specialist edge-case work — uncommon formats, very large inputs, or pipelines that need scripting — is what dedicated desktop apps are for. This page handles the common case quickly.
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 background on the design choices behind robots.txt Tester: 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.
robots.txt Tester 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.
If you want to get the most out of robots.txt Tester, 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.
Open the workspace above to start using robots.txt Tester. The engine loads on the first interaction so the page itself stays light, and once the tool is warm it processes subsequent jobs quickly. The moment the page is interactive, the tool is ready to do real work on your file.
How it works
- 1Reach the robots.txt Tester page in your browser to begin.
- 2Select the developer 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.
- 4Hit the run button. standard browser APIs does the work in your browser tab.
- 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 robots.txt Tester.
- Compare two API responses to spot a regression.
- Decode a token to confirm its claims during a debugging session.
- Format a noisy log line into something a teammate can read.
- Inspect a regex against a test string before committing it.
- Convert between data formats while wiring up an integration.
- Inspect a payload during local development without writing a script.
- Validate a config blob before pushing to staging.
FAQ
What is robots.txt?
A text file at your site root that tells search engine crawlers which URLs they can or cannot access.
What rules are supported?
User-agent, Allow, Disallow, Sitemap, Crawl-delay, and Host directives.
Can I test a URL?
Yes — enter a URL path and user-agent to check if it would be allowed or blocked.
What errors are detected?
Invalid directives, conflicting rules, unreachable sitemaps, and syntax errors.
Wildcard patterns?
The tool supports * and $ wildcards in Disallow and Allow paths.
Private?
Yes — parsing runs locally.
Does Favtoo keep a copy of files I process with robots.txt Tester?
Favtoo keeps no copy of your file because Favtoo never receives your file. robots.txt Tester 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.
Why does robots.txt Tester feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 0 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.
Does robots.txt Tester ask for any browser permissions?
robots.txt Tester 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.
Does robots.txt Tester work with screen readers?
robots.txt Tester uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
How is robots.txt Tester different from desktop apps that do the same thing?
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. robots.txt Tester sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common developer utility operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Which file formats does robots.txt Tester accept?
The accepted formats are listed in the upload area on the tool itself. If your input is in a format that is not directly supported, convert it first using one of Favtoo's converter tools — every Favtoo converter outputs a file that is a clean input to the next tool in the chain.
Why did robots.txt Tester reject my input?
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.