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Web tools

10 browser-based web utility tools: HTTP status reference, MIME type lookup, user agent parsing, DNS queries, robots.txt validation, sitemap checking, link extraction, HTML-to-text conversion, and meta tag preview. No server, no account, no upload.

Browser-based · no account · no upload

Web tools

Why browser-based web utilities?

Web developers and SEOs spend a surprising amount of time bouncing between scattered online tools. Every tool on this page is a single focused utility that works in your browser — no Chrome extension, no signup, no page that mines your input for ad targeting. HTTP status codes, MIME types, and DNS records are publicly documented standards; there is no reason to send your queries to a proprietary server.

The robots.txt validator, sitemap validator, links extractor, HTML-to-text converter, and meta tags preview all use only browser APIs: DOMParser, XMLSerializer, URL, and fetch. The DNS Lookup uses Cloudflare's public DNS-over-HTTPS endpoint, and IP Info uses a public geolocation API — both queries go directly from your browser to those public services, not through jarvisbox.

Choosing the right tool

Debugging a redirect chain? The HTTP Status Reference lists every 3xx code with caching behaviour. Checking what content type your server should send for a .wasm file? Try MIME Type Lookup. Auditing SEO before a launch? Use Meta Tags Preview to see your Google snippet and social cards, Robots.txt Validator to confirm crawlers can reach your pages, and Sitemap Validator to catch malformed XML before submitting to Search Console.

常見問題

Do these web tools send my data to a server?
Most tools run entirely in your browser with no network requests. The DNS Lookup tool uses Cloudflare's public DNS-over-HTTPS API, and the IP Info tool queries a public IP geolocation API. In both cases your input goes to a third-party public API, not to jarvisbox servers. All other tools — robots.txt validator, sitemap validator, links extractor, HTML to text, meta tags preview — are 100% local.
What is an HTTP status code?
HTTP status codes are three-digit numbers returned by web servers to indicate the result of a client request. 2xx codes mean success, 3xx are redirects, 4xx indicate client errors, and 5xx indicate server errors. The HTTP Status Reference lists all standardised codes with explanations.
What is a MIME type?
A MIME type (Multipurpose Internet Mail Extensions) is a label that identifies the format of a file. Browsers use MIME types to decide how to handle a response — display it, download it, or pass it to a plugin. Examples: text/html for web pages, image/jpeg for JPEG photos, application/json for JSON.
What does the User Agent Parser do?
It takes a raw User-Agent HTTP header string and decodes it into human-readable components: browser name and version, operating system, device type (desktop, mobile, tablet), and rendering engine. Useful for debugging analytics data or testing server-side UA detection logic.
What DNS record types can I query?
The DNS Lookup tool supports A (IPv4 address), AAAA (IPv6), CNAME (alias), MX (mail server), NS (nameserver), TXT (text records including SPF, DKIM, DMARC), SOA (start of authority), and CAA (certificate authority authorization) records.
How does robots.txt validation work?
The Robots.txt Validator parses the file line by line, checking for correct User-agent, Allow, Disallow, Crawl-delay, and Sitemap directives. It also includes a URL tester: enter a path and select a bot to see whether that bot would be allowed to crawl it.
What does the Sitemap Validator check?
It parses the XML, verifies the root element is <urlset> or <sitemapindex>, checks that each <url> entry has a <loc>, validates that <lastmod> dates are ISO-8601 formatted, and that <changefreq> and <priority> values are within allowed ranges.
What is an Open Graph meta tag?
Open Graph (OG) tags are HTML <meta> elements that control how a page appears when shared on social media platforms like Facebook, LinkedIn, and Twitter. The Meta Tags Preview tool extracts og:title, og:description, og:image, and Twitter Card tags to show you exactly what the social preview will look like.
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