What 'technical SEO skills' actually means to an agency
Walk into an agency interview for a technical SEO role and you'll be asked to diagnose why a client's rankings fell after a site migration, or to explain how you'd fix a crawl budget problem. Nobody wants to hear you recite the definition of a canonical tag. They want to know whether you can find the fault and fix it before the client notices.
That gap between knowing the theory and doing the work is where most candidates lose the job. We've sat on both sides of the interview table, and the pattern repeats. The people who get hired can open a crawl report and tell you the three things that matter, not the thirty things that don't.
So here's an honest look at the technical SEO skills agencies are testing for in 2026, and how to show you actually have them.
Site audits: the skill everything else hangs off
Every agency runs audits. It's the first thing a new client gets, and often the thing that wins the pitch. If you can't run one properly, you're not much use on day one.
The tools are not the skill. Screaming Frog, Sitebulb and Ahrefs will all crawl a site and hand you a list of errors. Plenty of candidates can generate that list. Far fewer can read it.
Reading an audit means prioritising. A 40,000-URL crawl will flag thousands of 'issues', and most of them don't move the needle. Your job is to separate the noise from the two or three problems costing the client traffic. Orphaned pages that should rank. Faceted navigation that spawns millions of parameter URLs and eats crawl budget. A robots.txt rule quietly blocking a whole product category.
When we interview, we hand candidates a real crawl export and ask what they'd tackle first. The strong ones talk about business impact before they mention the tool. The weak ones read the error list from top to bottom.
If you're building this skill, audit a site you don't own. Pick a mid-size ecommerce site, crawl it, and write a one-page summary of the three things you'd fix and why. That document is worth more in an interview than any certificate.
Core Web Vitals and the INP shift
Core Web Vitals stopped being optional a while ago. Google confirmed them as a ranking signal back in 2021, and the metrics themselves have moved since.
The big change: in March 2024, Google replaced First Input Delay with Interaction to Next Paint (INP) as a Core Web Vital. If you're still talking about FID in an interview, you're signalling that you stopped reading two years ago.
Know the current thresholds. Google's 'good' bar is a Largest Contentful Paint under 2.5 seconds, an INP under 200 milliseconds and a Cumulative Layout Shift under 0.1, measured at the 75th percentile of real users. Those numbers come straight from web.dev, and you should be able to recall them without checking.
What agencies actually want is someone who can connect a bad score to a cause. A slow LCP usually traces back to a render-blocking resource, an unoptimised hero image or a slow server response. A poor INP points at heavy JavaScript blocking the main thread. You need to be comfortable in Chrome DevTools and PageSpeed Insights, and you need to know the difference between lab data and the field data in the Chrome User Experience Report.
Here's the honest part. Most Core Web Vitals fixes are development work, not SEO work. The valuable skill is translating a technical problem into a ticket a developer will accept, and arguing its priority against everything else in their sprint. Agencies that seat SEOs next to their development teams want people who can have that conversation without friction.
Structured data: past the basics
Structured data is one of the few technical wins an SEO can often ship without waiting on a developer, which is exactly why agencies value it. Get the markup right and a client's listings can pick up review stars, FAQ dropdowns or product pricing in the search results.
Knowing that schema.org exists is not a skill. Writing valid JSON-LD, testing it in Google's Rich Results Test and debugging why an enhancement isn't showing is a skill.
The common mistakes are worth learning before an interview, because you'll get asked about them. Marking up content that isn't visible on the page. Using Product schema on a category page. Leaving in review markup after Google tightened its rules on self-serving reviews. An agency wants proof you understand Google's guidelines on when a rich result actually appears, and can spot markup that will never earn one.
A practical way to prove it: take a client-style page, write the JSON-LD yourself, validate it, and be ready to explain every property. That beats saying you've 'worked with schema' on your CV.
Log file analysis: the skill that separates senior from junior
This is the one that gets skipped, and it's often the one that gets you hired at a higher band.
Log file analysis means reading your server's raw access logs to see exactly how Googlebot crawls a site. Not what a third-party tool estimates. What the bot actually did, request by request.
For a small brochure site, it barely matters. For a large ecommerce or publisher site with hundreds of thousands of URLs, it's the difference between guessing and knowing. Logs tell you which pages Google never visits, how much crawl budget is wasted on redirects and parameter URLs, and whether your most important pages are crawled often enough to keep rankings fresh.
The skill is part technical, part analytical. You need to get hold of the logs, which is often the hardest part because it means talking to the client's hosting team. Then you parse them, verify that a request claiming to be Googlebot really is, and turn millions of lines into a clear story about crawl priorities. Screaming Frog's Log File Analyser and the ELK stack are common tools, but plenty of good analysts still start in a spreadsheet or with a few grep commands.
If you can walk into an agency interview and describe a time you found wasted crawl budget in a log file and what you did about it, you've marked yourself as more than a junior. Most candidates can't.
The skills agencies quietly weight just as heavily
Technical ability gets you shortlisted. These get you the offer.
Communication comes first. An agency SEO spends a large chunk of the week explaining technical findings to clients with no technical background, and to developers who have plenty and will push back. If you can't make a canonical issue sound urgent to a marketing manager, your audit sits in a drawer.
Then there's a working grasp of how modern sites are built. JavaScript frameworks, headless CMS setups and CDNs have changed what technical SEO involves. You don't need to ship production code, but you should understand how a React site renders and why that affects what Googlebot sees. We've written more about how this shapes the day job in what an agency SEO role actually looks like.
Curiosity matters more than any single tool. Google ships changes constantly, and the tactic you learned this year may be irrelevant next year. Agencies hire people who read the release notes, run their own tests, and treat a ranking drop as a puzzle rather than a panic.
How to show these skills before anyone asks
Certificates carry less weight than most candidates think. A portfolio of real problems solved carries far more.
Build a case study, even a small one. Take a site, find a genuine technical issue, document how you diagnosed and fixed it, and record the result. A candidate who arrives with a two-page write-up of a real crawl budget fix beats one with a wall of course badges every time.
Keep a test site too. It costs a few pounds a month and lets you break things safely: experiment with structured data, see how different rendering setups affect crawling, and watch what Search Console does when you change a directive. Interviewers can tell within minutes who has done this and who has only read about it.
And be honest about the gaps. Nobody expects a mid-level candidate to have deep log file experience. Saying 'I've read logs on smaller sites and I want to work at bigger scale' lands far better than bluffing and getting caught on the follow-up question.
Where the roles are
Demand for technical SEO hasn't softened, even as generative search changes how results appear. Agencies still need people who can keep large sites crawlable, fast and correctly marked up, and those skills transfer across every client an agency takes on.
If you're building the skills above and want to see who's hiring, our SEO jobs board lists current agency roles across the UK. Read a few technical SEO specs, note which skills come up again and again, and point your learning at those.
Get the fundamentals solid, prove them with real work, and stay curious about what Google changes next. That's what agencies are actually buying in 2026.
