django-devbar 0.4.0

Lightweight performance devbar for Django

django-devbar

Lightweight performance devbar for Django. Shows DB query count, query duration, application time, and detects duplicate queries with visual severity indicators.

Normal operation – showing query count, duration, and application time:

Duplicate queries detected – severity indicator and details shown:

[!WARNING] This package is experimental and may introduce breaking changes in minor versions.

Motivation

While Django Debug Toolbar is a proven tool trusted by countless projects, django-devbar explores a different approach to development debugging:

• Minimal setup — just add middleware, nothing else required
• Browser DevTools integration — Chrome extension panel works with any response type, including JSON
• Zero extra dependencies — only requires Django
• Lower overhead — no extra requests to debug endpoints
• Non-intrusive — HTML bar is optional; works via headers and DevTools panel alone

Installation

# Using uv (recommended)
uv add --dev django-devbar

# Or using pip
pip install django-devbar

Add to your middleware as early as possible, but after any middleware that encodes the response (e.g., GZipMiddleware):

MIDDLEWARE = [
    "django.middleware.security.SecurityMiddleware",
    "django_devbar.DevBarMiddleware",
    # ...
]

Configuration

All settings are optional. Configure via a DEVBAR dict in your Django settings:

DEVBAR = {
    "POSITION": "bottom-right",  # bottom-right (default), bottom-left, top-right, top-left
    "SHOW_BAR": None,  # follows DEBUG; set True/False to override
    "ENABLE_DEVTOOLS_DATA": None,  # follows DEBUG; set True/False to override
}

Response Headers

Django DevBar adds HTTP response headers with performance metrics:

• Server-Timing (always present) – Standard HTTP header with database, application, and total time metrics. Visible in Chrome DevTools Network tab under Timing.

An additional header is included by default in DEBUG mode:

• DevBar-Data - JSON header with comprehensive metrics including duplicate query details

This is useful for:

• API endpoints where the HTML overlay can't be displayed
• Automated testing to assert performance metrics (e.g., fail CI if query count exceeds a limit)
• Browser extensions that need detailed duplicate query information

Server-Timing format

Server-Timing: db;dur=87.50, app;dur=41.30, total;dur=128.80

Chrome Extension

View Django DevBar metrics directly in Chrome DevTools with the official extension.

See chrome-extension/README.md for more details.