# Installation
## Require the `gem`
The debugbar is installed like any other gem. Add it to your Gemfile, then run `bundle install` to install it.
As of today, you should only run the debugbar in development.
```ruby
group :development do
gem 'debugbar'
end
```
## Render the debugbar
### With the ERB helper
In your layout, make sure the debugbar is rendered via the view helper.
```erb
...
<%= debugbar_head if defined? Debugbar %>
...
<%= debugbar_body if defined? Debugbar %>
```
### Without the ERB helper
If your application doesn't use the `erb` view helper, you can render the debugbar manually.
This can be useful if your frontend is an SPA and the shell isn't rendered by Rails.
In your `index.html` file, make sure the following code is added:
```html
...
```
Note that if you changed the route prefix in your configuration, you'll need to update the url in the script tag.
## Puma configuration
**It's recommended to run Puma in single mode**! Rails uses single mode by default in dev but if you
modified it, set `WEB_CONCURRENCY` env var to 0. Puma cluster mode [requires extra configuration](/docs/puma-cluster-mode).
## Troubleshooting
If you run into any error, please open a GitHub issue with as much information as possible.
There is also a dedicated [Troubleshooting section](/docs/troubleshooting/).