FastAPI is API-first, but server-side rendering is still essential for dashboards, admin panels, and SEO-sensitive pages. Rendering HTML on the server allows tight coupling between backend data and presentation while reducing frontend complexity. This approach is particularly effective for internal tools and data-driven views.
Setting Up Jinja2 Templates
FastAPI integrates with Jinja2 through Starlette’s templating engine. Templates are stored in a dedicated directory and rendered explicitly from route handlers. Each rendered template must receive the request object to enable URL generation and context-aware rendering.
from fastapi import FastAPI, Requestfrom fastapi.templating import Jinja2Templatesapp =FastAPI()templates =Jinja2Templates(directory="templates")@app.get("/")defhome(request: Request):return templates.TemplateResponse("index.html",{"request": request,"title":"FastAPI with Jinja2"})
HTML Template Structure
Jinja2 templates define the HTML structure and dynamic placeholders rendered by FastAPI. Variables passed from route handlers are interpolated safely into the HTML. Keeping templates focused on presentation avoids mixing business logic with UI concerns.
Passing Data from Routes to Templates
Data is passed from FastAPI routes to templates using a context dictionary. This enables dynamic rendering of lists, tables, and computed values directly in HTML. Explicit data passing keeps dependencies clear and templates predictable.
