SEO is two jobs that are often confused. One is technical and belongs in development. The other is about content and reputation and cannot be built in.
What development should handle
- Crawlable pages. Real links between pages, one address per page, the main text present in the HTML the server sends.
- Clear titles and descriptions that are specific to each page.
- One clear heading structure with a single main heading per page.
- Correct status codes. A removed page returns 404 or a redirect, not a blank page that looks fine.
- A sitemap and sensible robots rules, and no accidental “do not index” left over from development.
- Speed and mobile layout, which affect visitors directly.
- Redirects when addresses change.
What development cannot do
It cannot make people search for what you offer, and it cannot make a thin page deserve to rank. Pages that help a reader better than the alternatives, in language people actually use, are what search engines are trying to find.
A caution about promises
Be sceptical of anyone who guarantees positions or traffic. Search results depend on competitors, your site’s history and changes outside anyone’s control. A sound foundation and useful content make results possible; they do not make them certain.
Google’s own starter guide, linked below, is short and worth reading before you hire anyone for SEO.