django-devbar

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

Note: This package is experimental and may introduce breaking changes in minor versions.

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, bottom-left, top-right, top-left
    'SHOW_BAR': None,            # None (default) = follows DEBUG, or True/False to override
    'SHOW_HEADERS': False,       # Add X-DevBar-* headers to responses
}

Response Headers

When DEVBAR = {'SHOW_HEADERS': True}, performance metrics are added as HTTP response headers. 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)
• Monitoring tools that can capture and aggregate header values

Headers included:

Header	Example	Description
DevBar-Query-Count	12	Number of database queries executed
DevBar-DB-Time	87ms	Total time spent in database queries
DevBar-App-Time	41ms	Application time (total time minus DB time)
DevBar-Duplicates	3	Number of duplicate queries detected (only present if duplicates found)