Do FDEs actually code?

Yes. Writing production code is what separates an FDE from a solutions engineer or a consultant. But the code looks different from core product work, and the split with client time shifts during an engagement.

What kind of code

• Integrations between the product and the customer's systems: APIs, webhooks, CRM and ERP connectors.
• Data pipelines that get the customer's data clean and where it needs to be.
• Applied AI systems: retrieval over the customer's documents, agents with tools, and the evals and guardrails around them.
• Glue and tooling: scripts, small dashboards, deployment configuration.

It is usually shipped faster and against messier constraints than product code, and it has to run inside someone else's infrastructure.

How the split changes

Early in an engagement, discovery and scoping take more of the week. In the build phase, most of the week is engineering. Near handover, documentation and training take over again. Across a typical week you do both, which is why the role suits people who enjoy switching between the two.

Why it matters for your switch

If you come from a client-facing role, production code is the gap to close: see the solutions engineer switch plan. If you are already an engineer, the code will feel familiar; the client work is the new part.