About OnPageKit
On-page SEO tools that run in your browser.
The problem this kit is aimed at
On-page SEO comes down to a handful of small, exact artefacts: a title that survives truncation in the results page, a canonical that names the URL you actually want indexed, a robots directive nobody left on noindex after a staging deploy, a robots.txt that does not quietly wall off the one directory you needed crawled. Every one of those fails silently. A page stops showing up, weeks pass, and no error is raised anywhere in your stack or your dashboards.
The free web is not short of tools for writing that markup. It is short of ones you can use before launch. Most ask for an email address before showing a preview, and the crawler-based ones fetch the address you give them from their own infrastructure, which is no help at all while the site sits behind a staging password or exists only in a branch on your machine.
This kit takes the opposite approach: you supply the values, the browser assembles the output, and the page never has to be reachable by anyone but you. Two groups cover what is here:
- Generators — Produce the markup and files search engines expect.
- Checkers — Paste your markup and see what a crawler makes of it.
Everything is assembled locally
The generators and checkers are compiled into the page as scripts. Fill in a field or paste a head block, and the parsing, counting and rendering all take place inside the browser tab in front of you. No copy of your draft is transmitted, because these tools hold no endpoint to transmit it to.
For SEO work that matters more than it might sound. Draft titles for a client rebrand, a canonical strategy for a migration that has not been announced, or a robots.txt for a domain still under embargo can all be worked on here without any of it becoming a third party’s record. And because the page holds no network dependency once opened, an aeroplane or a locked-down corporate network changes nothing about how it behaves.
Things you will not find here
No registration step, no trial that expires, no export limit, no stored projects. Drafts are not remembered between visits: this domain is served as static files, and behind a generator or a checker sits no application at all — neither a record to keep nor an account to hang one on.
Being exact about that matters, so here is the qualifier. A single endpoint does run on this domain, and its whole job is to take the two feedback forms described below and post them onward as an email. It is not involved in any tool, it is dormant until you press a send button, and the privacy notice enumerates what a submission actually contains.
Who maintains it
Revin runs OnPageKit. Revin is a software consultancy; the day job is designing, building and looking after products for clients, several of whom are in the United Kingdom. This kit came out of that work, from tags we found ourselves writing by hand on project after project.
How the output is kept correct
A generator that emits almost-right markup is worse than none at all, so the part that produces the output is isolated in its own module and pinned down by tests asserting the exact string it should return. Those tests face mutation testing before anything ships: the code under them is intentionally corrupted, and a mutation that no test catches is treated as a gap in the suite rather than a curiosity. Guidance published alongside a tool is reviewed by hand and revised when search engines change their behaviour, which they do.
Spotted a mistake?
Output that does not validate, advice that has gone stale, a counter that disagrees with what you see in the results page — please say so, at Report a bug. Reaching that page from a tool marks the tool for you automatically; what remains is naming the input you gave and the output it produced. An address to reply to is welcome but never required.
And when the gap is a whole tool rather than a defect, Suggest a tool is where that goes. The roadmap for this kit is not a strategy document; it is a list of jobs people wrote in to say they were still doing in a spreadsheet.
Also from us
DevToolBench follows the same principles for developer utilities rather than search markup.