Squarespace is built around a promise that the platform makes the technical decisions for you. That is genuinely useful until the day one of those decisions is the thing standing between you and something you need.
The constraints that bring people to these guides are mostly about control rather than quality. Markup and structured data are largely the platform's to decide, code injection has boundaries, and template behaviour is not yours to override past a certain point. None of that makes a Squarespace site bad, and plenty of them perform well. It does mean that when a specific requirement lands outside what the platform exposes, there is often no configuration that reaches it.
So the useful question in this cluster is not whether Squarespace is good for SEO in the abstract. It is whether the specific thing you need to change is something the platform lets you change. Several of these posts work through that check, because it usually resolves the decision faster than any general comparison does.
For sites where the answer is that the requirement sits outside the platform, our Squarespace migration service describes what a rebuild covers and what is handed over at the end.
Compare Squarespace with a custom website across editing, features, performance, export, SEO, commerce fees, ownership, lifecycle cost and migration risk.
Measure representative routes, inspect page weight, fonts, custom code, third parties and redirects, then choose an in-platform fix or a scoped migration.
A source-led audit of Squarespace crawlability, page controls, content, structured data and route-level performance before deciding to optimize or migrate.
Past the reading stage?
These guides describe the decision. If you have made it and want the work scoped against your own site, the commercial terms, acceptance criteria, and exclusions are on one page.