A Practical Technical SEO Checklist for Agencies and Developers

When I started doing technical SEO audits for agencies, I quickly learned that the difference between a report that gathers dust and one that actually gets implemented comes down to one thing: clarity. Developers don't have time to wade through vague recommendations. They need a technical seo checklist that maps each finding to a specific fix, ranked by impact. Over the years I have refined a process that starts with the fundamentals and works up to the edge cases. Here is what that looks like in practice.

Start with Crawlability and Indexation

The first thing I check is whether search engines can actually reach the content. If a page is blocked by robots.txt or carries a noindex meta robots tag, nothing else matters. I use Screaming Frog or another SEO spider to simulate a crawl of the site. The spider picks up every URL it can find, and from there I look for patterns that signal trouble.

One common issue is a misconfigured robots.txt that accidentally blocks critical resources like CSS or JavaScript files. Google Search Console's URL inspection tool will tell you if Googlebot sees a blocked resource. If the page renders poorly because of blocked assets, that can hurt your rankings even if the text is fine. I also check that the sitemap.xml is submitted to Google Search Console and that it only contains canonical URLs. A sitemap with 404s or redirect chains wastes crawl budget.

Speaking of canonical tags, I see a lot of confusion around them. The canonical tag should point to the version of the page you want indexed. If every paginated page canonicalizes to the first page, Google may never see the second or third page. That is a lost opportunity for long-tail traffic. The same goes for self-referencing canonicals on the homepage. They are not always needed, but they do no harm and prevent weird syndication issues.

Check On-Page Signals Beyond Keywords

After the crawl is clean, I move to on-page elements. ALT text on images is a classic thing that slips through the cracks. A site with thousands of product images might have ALT text that says nothing or just repeats the filename. That is a missed chance to tell search engines what the image shows, and it hurts accessibility too.

I also look at structured data. Many sites have some form of schema markup, but it is often incomplete or incorrect. Using Google's Rich Results Test or a tool like Ahrefs can show you which rich results you qualify for. A common mistake is using the wrong type of schema for a local business or forgetting to add the review markup on product pages. Fixing structured data can improve click-through rates more than most people expect.

Core Web Vitals come into play here as well. Lighthouse and PageSpeed Insights give you a score, but the real value is in the diagnostics. I look at Largest Contentful Paint and Cumulative Layout Shift specifically. A big shift often means a script is loading late and moving content around. That is a user experience problem and a ranking factor. I also check server response times. A slow Time to First Byte can kill your Core Web Vitals scores even if the frontend is optimised.

Dive Into JavaScript Rendering

JavaScript rendering is probably the area where most audits are too shallow. A lot of modern sites load content via JavaScript after the initial HTML is served. If Googlebot cannot render that JavaScript, the content may as well be invisible. I use the URL inspection tool in Google Search Console to see the rendered version of a page. If the rendered HTML is missing key text or links, that is a red flag.

One client had a dynamic FAQ section that loaded via an API call. The API was blocked by robots.txt, so Google never saw the questions or answers. The fix was simple: serve the content inline or allow the JavaScript resource. A technical seo checklist should always include a step for testing rendered content. I run a few sample URLs through the mobile-friendly test and check the rendered source. If something is missing, I dig into why.

For sites that rely heavily on client-side rendering, I also look at the meta robots tag. Sometimes a developer adds a noindex tag on a page that only appears after JavaScript loads. That tag will not be seen by Googlebot if the JavaScript is not executed. So the page might get indexed when the developer intended it to be hidden. That is a mess to clean up later.

Evaluate Redirects and Internal Links

Redirect chains are one of those things that build up over time. A page gets moved, then moved again, and eventually you have a chain of three or four redirects before the final URL. Each redirect adds latency and uses crawl budget. I use Screaming Frog to map out the redirect paths. Any chain longer than two hops should be flattened to point directly to the final URL.

Broken links are another easy win. A broken link on a high-traffic page can frustrate users and waste link equity. I run a crawl with any SEO spider to find 4xx and 5xx status codes. Then I check whether the broken URL should redirect to a live page or whether it was removed intentionally. If the content is truly gone, I set up a 410 Gone response so crawlers stop trying.

Internal linking is less obvious but just as important. I look for orphan pages: pages that have no internal links pointing to them. Orphan pages are invisible to users and hard for search engines to find. A quick way to spot them is to compare the list of all URLs in the sitemap against the list of URLs found during a crawl. Any page in the sitemap that the spider never reached is an orphan. Adding a link from a relevant category page or from the sitemap itself can bring it back into the index.

Mobile-First Index and Performance

Google uses the mobile version of a page for indexing and ranking. That means the mobile experience is the one that matters. I check whether the mobile viewport has the same content as the desktop view. Sometimes responsive sites hide content on mobile using display:none, which can be fine as long as the HTML is still there. But if the mobile version loads different content via a separate template, you need to make sure the canonical URL matches the mobile URL.

I also look at page speed from the mobile perspective. Tools like PageSpeed Insights give a separate mobile score. I focus on the Largest Contentful Paint time because that is when the user actually sees the main content. If a hero image takes five seconds to load, the user has already left. Compressing images, enabling browser caching, and reducing the number of scripts can all help.

Google Analytics can give you the real story here. If you see a high bounce rate on mobile for a specific page, check its load time. Often the two correlate. I once worked on a site where the mobile bounce rate was 80% for the product pages. After optimising images and deferring non-essential scripts, the bounce rate dropped to 55% and organic traffic grew by 30% in two months.

Prioritise and Present the Fixes

The whole point of a technical seo checklist is to turn findings into action. I group issues by impact and effort. A broken canonical tag that affects hundreds of pages is high impact and low effort. A JavaScript rendering issue that requires a rewrite is high impact but high effort. The client or agency needs to see that distinction so they can decide what to tackle first.

I also include a short explanation of why each fix matters. Developers are more likely to implement a change when they understand the reasoning. For example, I might note that a missing ALT text on a product image means the page misses out on image search traffic and accessibility compliance. That is more persuasive than just saying "add ALT text."

Finally, I recommend re-running the audit after fixes are deployed. Tools like Ahrefs, Screaming Frog, and Google Search Console make it easy to verify that a change worked. The redirect chain that was flattened should now show a single 301. The noindex tag that was blocking a landing page should be removed. The structured data should pass the rich results test.

A good technical seo checklist is never static. It evolves with the site and with search engine updates. But the core steps stay the same: crawl the site, check indexation, verify rendering, audit on-page elements, and clean up redirects. If you cover those areas, you will catch most of the issues that hold a site back.