Jinja2

Jinja2 is the de facto Python templating engine and it shows in its polish. The template syntax is intuitive and powerful - filters, macros, template inheritance, and includes work exactly as you'd expect. The API is straightforward: `Environment().from_string()` or `get_template()` gets you 90% there. Error messages are excellent, showing line numbers in your templates with helpful context when variables are undefined or filters fail.

The documentation is comprehensive with solid examples, though you'll find yourself referencing it often for filter syntax. IDE support is mixed - PyCharm has decent template syntax highlighting, but VS Code needs extensions. AutoEscape is enabled by default for HTML which is great for security, though switching contexts (HTML vs JSON vs plain text) requires understanding the nuances.

The biggest pain point is type safety. There's no native way to type-check template variables or ensure templates receive correct context. Runtime errors are clear, but you only discover type mismatches when rendering. The `select_autoescape` function and custom filters are powerful but require reading docs carefully to get configuration right.

Jinja2 is the backbone of Python templating and it shows in its polish. The template syntax is intuitive and powerful - filters, macros, template inheritance, and block composition all work exactly as you'd expect. Error messages are generally helpful, pointing to line numbers in templates when things break, though cryptic `UndefinedError` messages can be frustrating when variables are missing.

The documentation is comprehensive with good examples, though it's organized more as a reference than a tutorial. Getting started is straightforward: `Template(string).render(context)` gets you going immediately. The `Environment` API for customization is well-designed, letting you control autoescaping, delimiters, and loaders cleanly.

The main DX pain point is the complete lack of type safety. There's no way to validate template variables against type hints, and IDEs can't autocomplete variables inside template strings. You're essentially working with stringly-typed code, which means runtime errors for typos. The sandboxed execution model is great for security but can surprise you when legitimate code fails silently.

Jinja2 is the de facto Python templating engine and for good reason - it's fast, feature-rich, and has excellent auto-escaping that prevents XSS by default in HTML contexts. The `autoescape=True` configuration is critical and thankfully well-documented, but you need to ensure it's enabled in every environment object you create. I've seen production issues where developers created ad-hoc Environment instances without it.

The security model is generally solid. Context-aware escaping works well for HTML, but you must be explicit about JSON, JavaScript, or URL contexts using custom filters. The sandbox mode (`SandboxedEnvironment`) is useful for user-generated templates but has had historical bypasses - CVE response has been reasonably quick, though you need to stay on top of updates. Template compilation caching can expose sensitive data in stack traces if not handled carefully.

Input validation is your responsibility - Jinja2 won't protect you from template injection if you allow untrusted template sources. The `select` and `attr` filters can be vectors for accessing unintended objects. Documentation around security best practices exists but could be more prominent.