Robots.txt Validator
Validate robots.txt syntax including directives, User-agent rules, Sitemap references, and Crawl-delay.
How it works
- 1Paste or type your text in the input field
- 2Click "Validate" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About Robots.txt Validator
Robots.txt Validator performs robots.txt validator as a focused single-page utility. Validate robots.txt syntax including directives, User-agent rules, Sitemap references, and Crawl-delay. Defaults are tuned for the common case so the first run is one click, with every option that matters exposed for the moments you need to fine-tune the result.
The right moment to reach for Robots.txt Validator is when you have a focused web and productivity 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.
Robots.txt Validator 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.
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.
On limits: 0 MB per file is the ceiling. Output formats and quality settings are listed in the controls panel above, and they apply to every run.
The heaviest users of Robots.txt Validator tend to be product managers comparing options, site owners auditing pages and teachers building resource lists. 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.
Robots.txt Validator returns the result as a download. If you are running multiple jobs, the output names will not collide as long as the input names differ. You can re-run with different settings as many times as you like; each run produces a fresh file with no caching trickery in between.
Robots.txt Validator sits in a small group of related tools. Useful neighbours include Sitemap XML Validator, Meta Tag Analyzer, Canonical URL Generator, and SEO Checklist Generator. They are designed to compose: the output of one is a sensible input to the next, so a multi-step task is usually a sequence of single-click operations.
Some notes on the design of Robots.txt Validator. 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.
A short note on how Robots.txt Validator came to look the way it does: every iteration started by watching how someone unfamiliar with the tool actually used it, then removing whatever got in their way. That is why the upload area dominates the screen, the run button is bigger than the secondary controls, and the result panel is unmissable when the job finishes.
If you also use a command-line tool for robots.txt validator, Robots.txt Validator 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.
Useful patterns when working with Robots.txt Validator: 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.
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.
Robots.txt Validator 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 Robots.txt Validator workspace above. The interface is a single page, so there is nothing to navigate.
- 2Drop a web utility 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.
- 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.
- 5Save the output when it is ready.
- 6Run additional jobs as needed. The same controls and defaults apply on every run.
Common use cases
- Create a placeholder image for a wireframe using Robots.txt Validator.
- Validate a setting before circulating it to a team.
- Run a one-off check during a meeting without context-switching.
- Compare two product variations side by side.
- Preview how a result looks before deploying it.
- Plan content without paying for a SaaS dashboard.
- Run a fast accessibility check before publishing.
- Audit a marketing page before launch.
FAQ
What is robots.txt?
A file at /robots.txt that tells search engine crawlers which pages to access or skip.
What is checked?
Syntax, directive ordering, URL formats, Sitemap references, and Crawl-delay values.
Common errors?
Missing User-agent, paths not starting with /, invalid Crawl-delay, and missing Sitemap URLs.
Private?
Yes — validation runs locally.
Wildcard support?
The validator checks syntax; wildcard (*) and end-of-string ($) patterns are valid in paths.
Sitemap directive?
Sitemap lines must contain a full URL (https://...) and can appear anywhere in the file.
Does Robots.txt Validator upload my file to a server?
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.
Is there a programmatic version of Robots.txt Validator?
Robots.txt Validator is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
How do I know I am using the latest version of Robots.txt Validator?
Robots.txt Validator 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.
How is Robots.txt Validator 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 Validator 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.
How long does Favtoo retain my data after using Robots.txt Validator?
Favtoo keeps no copy of your file because Favtoo never receives your file. Robots.txt Validator 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.
Are there any usage limits on Robots.txt Validator?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run Robots.txt Validator as often as you need; every run produces a full-quality result.
Does Robots.txt Validator work in Safari, Firefox, Chrome and Edge?
Robots.txt Validator 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.