A robots.txt file generator creates a small, plain-text crawler instruction file for one website without sending configuration data to a server. The generator asks for the site's HTTP or HTTPS origin and the overall policy you want compliant crawlers to follow, then emits a UTF-8 text file built around one user-agent group and a sitemap line. RFC 9309 defines how that text is parsed, so the generator sticks to the standardized group-and-rule model instead of trying to manage every search engine's private extensions. Wildcard asterisks and the trailing dollar sign are preserved because the protocol defines them; hash signs are rejected so a user-entered rule cannot accidentally become a comment. Path rules match against URL paths from the first octet, with case sensitivity and longest-match behavior specified by the same RFC. The output is meant to be downloaded, compared against the current production file, and then published as /robots.txt at the exact scheme, host, and port it governs.
What a Robots.txt File Generator Actually Does
A robots.txt file lives at the root of a website and tells compliant crawlers which paths they may request. Writing one by hand means picking a user-agent, deciding between Allow and Disallow rules, and remembering the exact path syntax the protocol expects. A robots.txt file generator removes the typing and the second-guessing by turning a few deliberate choices into a text file you can copy or download.
The Robots.txt Generator follows that approach in the browser. You enter the site origin, choose whether compliant crawlers should access everything, avoid selected paths, or avoid the entire site, and the tool produces plain UTF-8 text with one wildcard user-agent group and a sitemap URL derived from that origin. Nothing is sent to a remote service during generation, and every entered path or generated line stays in the current tab.
The Three Policy Modes at a Glance
Every robots.txt file is shaped by a single top-level policy choice, even when it grows more specific later. The generator surfaces three modes that cover the everyday cases so you are not pretending to model behavior the protocol does not define.
| Mode | What the generator writes | When to use it |
|---|---|---|
| Allow all | User-agent: * followed by Allow: / | Default open site where compliant crawlers may fetch anything |
| Selective disallow | User-agent: * followed by one Disallow line per entered path | Mostly open site with specific areas (drafts, internal search, admin) off-limits |
| Block all | User-agent: * followed by Disallow: / | Temporary offline site, staging environment, or a placeholder that should not be crawled at all |
All three modes then receive the same single trailing line: Sitemap: followed by the normalized origin plus /sitemap.xml. If your real sitemap lives elsewhere, edit that line before publishing because the tool only knows the origin plus that default path.
Generate and Inspect Your robots.txt File
The generator turns the policy choice into text in three short steps. Treat them as a checklist rather than a one-click action, because the result governs a live site and a typo here can quietly block the wrong pages.
- Enter the complete HTTP or HTTPS URL for the website origin in the input field. The generator reduces any page path, query, or fragment down to the origin so the sitemap line does not accidentally inherit an unrelated route. Explicit ports are preserved.
- Choose the overall crawler policy. For selective mode, enter one disallowed path per line. Each non-empty rule must start with a slash, exact duplicates are removed in the order they were first entered, and the list is capped at 50 rules. Hash signs are rejected so a user-entered rule cannot become a comment, while wildcard asterisks and a trailing dollar sign are kept because the protocol defines them as special matching characters.
- Generate the text and inspect it in the output panel. Compare it with the current production file, preserve any intentional crawler-specific groups you want to keep, then download the result and publish it as /robots.txt only after that comparison.
Anatomy of the Generated Output
Allow all mode produces three lines:
User-agent: *
Allow: /
Sitemap: https://example.com/sitemap.xml
Block all mode produces the same shape with a different rule:
User-agent: *
Disallow: /
Sitemap: https://example.com/sitemap.xml
Selective mode writes the same User-agent: * header, then one Disallow line per accepted path, then the Sitemap line. Each block follows the RFC 9309 model: a group begins with User-agent, followed by Allow or Disallow rules. The wildcard product token applies when a crawler has no more specific matching group, which is why this generator intentionally emits one general group rather than pretending to manage bot-specific extensions.
Path matching begins at the start of a URL path, so /draft means anything beginning with /draft while /draft$ means only that exact path. According to RFC 9309, crawlers compare paths case-sensitively and use the most specific matching rule; consequently /Private and /private can mean different things, and Disallow: /draft does not necessarily express the same intent as Disallow: /draft$.
Path Rules That Survive the Generator (and Why)
Selective mode accepts one path pattern per line and applies a small set of guardrails before adding the rule to the output. Knowing those guardrails prevents the kind of mistake that quietly blocks the wrong pages.
- Leading slash: every rule must start with /. Allow and Disallow patterns match URL paths from their first octet, and valid path patterns begin with a slash.
- Wildcards and anchors: asterisks and a trailing dollar sign are preserved because the protocol defines them as special matching characters. A mid-string asterisk is preserved verbatim; only the trailing $ is treated as the path-end anchor.
- Case sensitivity: RFC 9309 specifies case-sensitive comparison, so /Private and /private are different rules. Review capitalization before publishing.
- No comments: a hash sign would turn the rest of the line into a comment, so the generator rejects it rather than risk silently stripping your intent.
- Deduplication and limit: exact duplicates are removed in the order they were first seen, and the list is limited to 50 rules.
For a fuller mental model of how rules combine in real configurations, this practical guide to creating a robots.txt file walks through the longer examples the generator does not aim to handle.
Publishing /robots.txt at the Right Origin
The file the generator produces is the right text, but only if it is served from the right place. According to Google's documentation on creating a robots.txt file, it must be published as /robots.txt at the top level of the exact scheme, host, and port it governs. Use a lowercase filename and serve it as text/plain. A file placed on a subdirectory, another subdomain, or a different protocol does not govern the intended origin, even if the contents look correct.
A quick mental check before pushing live: open the production URL with /robots.txt appended and confirm the new text is what comes back. Keep a copy of the old file for rollback in case the change blocks something you did not mean to block. If your real sitemap sits at a different path, edit the Sitemap line before uploading; the generator only knows the origin plus /sitemap.xml, so anything else has to be entered by hand.
The published file is also public. Every listed path is visible to anyone who requests /robots.txt, so do not treat a Disallow line as a way to hide a sensitive route. Use server-side authentication and authorization for that, and use page-level indexing controls (such as a robots meta tag) when you need a finer-grained decision than path-level disallow allows.
What the Generator Doesn't Do
The generator is narrow on purpose, which is also a checklist of things you still own before the file is truly live.
- It does not fetch the existing live file. Comparing the new text against the current production file is your step, not the tool's.
- It does not validate server responses. Whether the file is served as text/plain at the right origin is something to confirm with a curl or a browser request after publishing.
- It does not submit the file to a search engine. Refreshing a crawler cache and submitting updated robots.txt files happens in search-engine tools, not in a generator.
- It does not add Crawl-delay. That directive is outside RFC 9309 and is not supported consistently across crawlers, so emitting it would be a guess rather than a guarantee.
- It is not an access control. Compliant crawlers may honor the requests, but a malicious client can ignore them, and blocking crawling does not guarantee that a URL disappears from search results.
In practice, that means a generated robots.txt file is the start of a workflow rather than the end. Generate the text, compare it with the current file, edit the sitemap line if needed, publish at the exact origin, verify with a real request, and test important public and blocked URLs with the relevant search-engine tester where available.