Partly, and the part they can do is genuinely valuable. The question is worth answering precisely rather than defensively, because a good developer covers more SEO ground than most agencies admit, and less than most business owners assume.
What developers usually do well
These are engineering problems with correct answers, and a competent developer will handle them better than most marketers.
- Correct status codes, redirects and canonical implementation.
- Fast, well-built pages, which covers most of Core Web Vitals.
- Clean, stable URL structures.
- Server-side rendering and crawlable markup. See SSR vs CSR.
- Valid structured data.
- Accessible HTML, which produces good heading structure as a by-product.
A site built by a developer who understands these starts from a much better position than one that does not, and needs less remediation later.
What they usually do not
Not through lack of ability, but because these are commercial and editorial judgements rather than technical ones.
- Deciding which searches are worth competing for. That is a commercial decision about demand, competition and margin.
- Deciding which page owns which query, which prevents your own pages competing. See keyword mapping.
- Judging whether content answers the query better than what ranks. That requires reading the results, not the code.
- Diagnosing declines, which needs search and analytics data rather than logs alone.
- Knowing when a technically fine page is the wrong page type for the query.
The failure mode in each direction
Developer-led SEO
Produces a technically excellent site that targets the wrong things, or nothing in particular. Everything validates, nothing ranks, and the usual conclusion is that SEO does not work.
Marketing-led SEO with no developer
Produces recommendations nobody implements. The audit is correct and the site does not change. This is the more common and more expensive failure. See when an SEO agency is not getting results.
The arrangement that works
Developer owns implementation; someone owns direction. That someone can be a consultant, an in-house marketer or the business owner, provided they are actually making the decisions rather than assuming the developer is.
- Agree explicitly who decides what the site targets. This is the gap in most arrangements.
- Give developers specifications rather than goals. “Fix our SEO” is not actionable; a ticket describing current and intended behaviour is.
- Involve them before structural decisions, not after.
- Accept that a developer saying a recommendation is not implementable as written is frequently correct.
What to ask your developer
- Are our pages server-rendered, and is content in the initial HTML?
- Do URLs that do not exist return 404, or a 200 with an error message?
- Are internal links real anchor tags?
- Do redirects resolve in one hop?
- Is there anything in robots.txt or the headers preventing indexing?
A developer who can answer those confidently has covered the technical foundation. What remains is targeting and content, which is a different job.
Frequently asked questions
Can my developer replace an SEO consultant?
For technical implementation, often. For deciding what to compete for and whether content is competitive, generally not, and it is unfair to expect it.
Should I hire a developer who says they do SEO?
Ask which parts. Someone who says they handle technical foundations and not strategy is being accurate. Someone claiming to handle all of it may be overstating.
Our site was built well but does not rank. Why?
Almost certainly targeting or content rather than technical. A technically sound site still has to compete on what it says and which queries it addresses.
Who should own SEO internally?
Whoever makes commercial decisions about which customers you want, with a developer implementing. Ownership sitting entirely with development usually means nobody owns the direction.
Consulting CTA
If your site is technically sound and still not ranking, book an SEO consultation to work out whether the gap is targeting, content or structure.