A technical SEO agency finds, prioritises and specifies search issues. Your developer builds and tests the fixes. The best results come from both.
A technical SEO agency should find, prioritise and specify the problems holding your site back in search. Your developer should build, test and release the fixes. When each side sticks to what it does best, and they talk to each other, technical SEO work gets done faster and breaks less.
Many businesses assume their web developer “does the SEO”. Developers build sites that work, load and look right. Search engines care about some of the same things and a lot of different ones: how pages are crawled, which version gets indexed, how content is rendered, and how signals flow between pages.
That gap is where most technical SEO problems live. Neither side is at fault. They’re simply looking at the site through different lenses.
What a technical SEO agency does
A technical SEO specialist diagnoses why search engines struggle with your site and decides what matters most. Typical work includes:
- Crawling the site to find broken links, redirect chains, duplicate pages and orphaned content (see how to do a site crawl).
- Checking which pages Google indexes and why others are left out.
- Reviewing how JavaScript content renders for search engines.
- Analysing Core Web Vitals in field data, not just lab tests.
- Planning site structure, internal links and URL patterns.
- Writing structured data and checking it’s valid.
- Planning and checking migrations so rankings survive a rebuild.
The output should be a prioritised list of issues, each with the business impact, a clear specification and a way to test that the fix worked. If you want the fuller picture, our guide to what technical SEO is covers the basics.
What your developer does
Your developer knows the codebase, the hosting, the CMS and the risks of changing them. Their job is to turn the specification into working code without breaking anything else. That means:
- Building fixes in a staging environment and testing them.
- Handling server settings, caching and redirects.
- Improving templates, scripts and image handling for speed.
- Releasing changes safely and rolling back if needed.
- Flagging when a fix would conflict with other plans or cost more than it’s worth.
A good developer will push back when a recommendation doesn’t fit how the site works. That’s healthy. The SEO side should be able to explain why a change matters so the two can agree a sensible route.
Who should fix what
Here’s how we’d usually split the common tasks:
| Task | Technical SEO agency | Developer |
|---|---|---|
| Crawl and indexing issues | Finds them, explains the cause, sets priority | Fixes templates, canonicals, robots rules |
| Redirects and migrations | Builds the redirect map, checks after launch | Puts redirects live on the server or CMS |
| Page speed and Core Web Vitals | Identifies the slow templates and causes | Optimises code, images, caching and hosting |
| JavaScript rendering | Tests what search engines can see | Changes how content loads or renders |
| Structured data | Writes the schema and validates it | Adds it to templates |
| Site structure and internal links | Plans the structure and linking | Builds menus, hubs and templates |
Some agencies can make simpler changes directly in a CMS like WordPress. That saves developer time for small fixes, as long as everyone agrees who changes what.
How to brief your developer on SEO fixes
Most SEO recommendations fail because the brief is vague. “Improve page speed” or “fix indexing” doesn’t give a developer enough to act on. A good technical SEO ticket includes:
- The problem, with example URLs.
- Why it matters, in terms of traffic, leads or risk.
- The fix, described clearly enough to build.
- How to test it, so both sides can confirm it worked.
- The priority, so it lands in the right sprint.
For example: “Product category pages with filters create thousands of duplicate URLs (example links). Google is spending crawl time on them instead of new products. Add a canonical tag pointing to the unfiltered category and block filter combinations in robots.txt. Test with a crawl and URL Inspection in Search Console. High priority.”
Signs the split isn’t working
Watch for these:
- Audits that sit unread because nobody owns the fixes.
- Fixes released without the SEO side checking them.
- A site rebuild planned without anyone from SEO involved.
- The same issues showing up in every audit.
Migrations are the biggest risk. A rebuild that changes URLs without a proper redirect plan can wipe out years of rankings. Bring the SEO side in at the planning stage, not the week before launch.
Do you need both?
Small sites on a standard CMS can often get by with a developer and an occasional technical audit. Larger sites, ecommerce stores, SaaS platforms and anything built on a JavaScript framework usually need both, working to a shared backlog. Speed work is a good example: our guide to improving Core Web Vitals and page speed shows how much of it depends on the two working together.
Our technical SEO agency team writes developer-ready tickets and checks every fix after release, so your developers spend time on the changes that matter. We do this for a lot of B2B SEO clients with small in-house dev teams. If you want a second pair of eyes on your site, book a free strategy session.
Related reading: our guides to JavaScript SEO and indexability.
Common questions
Can my web developer do SEO?
A developer can build most technical SEO fixes, and some know search well. Diagnosing crawl, indexing and rendering problems and deciding what matters most is usually a specialist job.
What is an SEO developer?
An SEO developer is a developer with search knowledge who builds technical SEO fixes such as redirects, structured data, rendering changes and speed improvements.
Who should handle redirects during a site migration?
The SEO side should plan the redirect map and check it after launch. The developer should put the redirects live and test them on the server or CMS.
How should SEO fixes be briefed to developers?
Each ticket should state the problem with example URLs, why it matters, the fix, how to test it and its priority, so it can go straight into a sprint.
