ReachKit vs Semrush
An on-page SEO checker tool reads a page's HTML and reports which of the things search engines look for — the title, the meta description, the heading structure, structured data, the canonical, image alt text — are missing or malformed. Semrush's lives at semrush.com/siteaudit, and on raw coverage it is the more thorough of the two. ReachKit checks 8 on-page signals rather than hundreds of issues, and spends the difference deciding which one you should fix first.
What Semrush's on-page SEO checker does better
It checks more, and that is not a small thing. Semrush's free SEO Checker covers four families ReachKit does not touch at all: off-page signals (backlinks, referring domains, authority scores), technical crawl access (robots directives, status codes, sitemap coverage, indexability), site performance (page speed, mobile friendliness, Core Web Vitals) and social-media visibility. If a slow server or a stray noindex is what is actually holding your pages back, Semrush will find it and ReachKit will not.
It also has somewhere to go next. The upgrade path from the free checker is Site Audit, which by Semrush's own description crawls your entire site rather than one page, checks for hundreds of technical and on-page issues, tracks progress over time, and lets you schedule automatic audits; Semrush One advertises 140+ technical and on-page checks. For a site with thousands of URLs, a whole-site crawl is the only honest way to audit it, and that is a genuine capability gap in ReachKit's direction.
And the output is well-built for a beginner: an overall SEO score, a prioritised to-do list, and a report that shows what passed as well as what failed, with each item explained in plain language.
Where it leaves a solo founder stranded
The free tier is one check per day. That is Semrush's own stated limit, and it is the wrong shape for how fixing a page actually goes: you change the title, you want to see whether the checker agrees, and you find out tomorrow. Anything past that first check is an upgrade, and the page quotes no price for it — the only free trial it names is seven days of Semrush, cancel anytime.
The deeper problem is what a long list is for. Hundreds of issues sorted by generic severity tells you what is wrong with the page; it does not tell you which of those things is costing you customers, because the checker has no idea what you sell or who you are competing against for it. Severity is a property of the issue. Impact is a property of your market, and it is the one a founder is actually trying to buy.
A marketing team has someone whose job is to close that gap. A founder has Tuesday evening.
What ReachKit does instead
ReachKit measures 8 on-page signals — page title, meta description, heading structure, content depth, structured data, canonical URL, social share tags, and images & alt text — straight out of your live HTML, and combines them by geometric mean with your raw search footprint into one 0–100 Discoverability Score. It is deterministic: the same URL produces the same score, because no language model is anywhere near the number. What it does not do is crawl your whole site, test your page speed, or look at your backlinks. Eight signals is the honest count.
The free on-page checker at reachkit.app/tools/on-page-check takes no signup and no email address, and allows 30 checks per hour from one address rather than one per day — enough to change a title, re-run it, and see the result while you still have the file open.
The paid plan is where the two products stop being the same kind of thing. Instead of a longer list, you get a ranked weekly action plan — one task surfaced per day — where every item cites the evidence it came from: the tag that is missing, the query your rivals rank for and you do not, the page outranking you. The next weekly scan re-measures the site, and where the score moved, the gain is attributed to the on-page fix you shipped rather than assumed.
The first scan is free; the weekly engine is €29.50/month — the 50% launch price, locked for life, normally €59.
Who should pick which
Pick Semrush if the question you are asking is "what is wrong with this site?" and you want the widest possible answer — especially if you suspect the problem is speed, crawlability or links, or if the site is big enough that auditing one page at a time is meaningless.
Pick ReachKit if the question is "what should I do this week?" — if you already suspect the answer is on-page, you would rather re-run a check ten times this afternoon than once a day, and you want the list to come back ranked by what it is worth rather than by how loud the issue is.
Feature by feature
| Capability | ReachKit | Semrush |
|---|---|---|
| Free on-page check with no signup | Yes | Partialone check per day |
| On-page signals measured from your HTML | Partial8 signals, in full | Yes |
| Page speed, Core Web Vitals, mobile | No | Yes |
| Backlinks & off-page authority | No | Yes |
| Whole-site crawl | No | Yes |
| Discoverability score (0–100) | Yes | Partialoverall SEO score |
| Fixes ranked by market impact, not severity | Yes | No |
| Fixes verified by your next weekly scan | Yes | No |
The verdict
- You need page speed, Core Web Vitals, backlinks or crawl access checked — ReachKit measures none of those.
- Your site is large enough that a whole-site crawl beats a page-at-a-time check.
- A marketer or agency on your project already reports through Semrush.
- One free check per day is not enough to iterate on a page you are editing right now.
- You want the list ranked by what it is worth to your market, not by generic severity.
- You would rather be told what to do this week than shown everything that is wrong.