diff --git a/pages/06.contribute/10.packaging_apps/60.advanced/20.config_panels/config_panels.md b/pages/06.contribute/10.packaging_apps/60.advanced/20.config_panels/config_panels.md
index a69beee2..c88a866c 100644
--- a/pages/06.contribute/10.packaging_apps/60.advanced/20.config_panels/config_panels.md
+++ b/pages/06.contribute/10.packaging_apps/60.advanced/20.config_panels/config_panels.md
@@ -7,4 +7,295 @@ routes:
   default: '/packaging_config_panels'
 ---
 
-TODO / FIXME ...
+# Configuration panel for apps
+Configuration panels for apps allows to let instances adminitrators manage some parameters or runs some actions for which the upstream doesn't provide any configuration panels itself. It's a good way to reduce manual change on config files and avoid conflicts on it.
+
+Those panels could aslo be used as interface generator to extend quickly capabilities of YunoHost (e.g. VPN Client, Hotspost, Borg, etc.).
+
+! Please: Keep in mind the YunoHost spirit, and try to build your panels in such a way as to expose only really useful parameters, and if there are many of them, to relegate those corresponding to rarer use cases to "Advanced" sub-sections.
+
+## How does config_panel.toml work
+
+Basically, configuration panels for apps uses at least a `config_panel.toml` at the root of your package. For advanced usecases, this TOML file could also be paired with a `config` script inside the scripts directory of your package.
+
+The `config_panel.toml` file describes one or several panels, containing some sections, containing some questions generally binded to a params in a configuration file.
+
+We supposed we have an upstream app with this simple config.yml file:
+```
+title: 'My dummy apps'
+theme: 'white'
+max_rate: 10
+max_age: 365
+```
+
+We could for example create a simple configuration panel for it like this one, by following the syntax `\[PANEL.SECTION.QUESTION\]`:
+```
+version = "1.0"
+[main]
+
+[main.main]
+[main.main.title]
+ask.en = "Title"
+type = "string"
+bind = ":__INSTALL_DIR__/config.yml"
+
+[main.main.theme]
+ask.en = "Theme"
+type = "select"
+choices = ["white", "dark"]
+bind = ":__INSTALL_DIR__/config.yml"
+
+[main.limits]
+[main.limits.max_rate]
+ask.en = "Maximum display rate"
+type = "number"
+bind = ":__INSTALL_DIR__/config.yml"
+
+[main.limits.max_age]
+ask.en = "Duration of a dummy"
+type = "number"
+bind = ":__INSTALL_DIR__/config.yml"
+```
+
+Here we have created one `main` panel, containing the `main` and `limits` sections, containing questions according to params name of our `config.yml` file. Thanks to the `bind` properties, all those questions are bind to their values in the `config.yml` file.
+
+### Questions short keys have to be unique
+For performance reasons, questions short keys should be unique in all the `config_panel.toml` file, not just inside its panel or its section.
+
+So you can't have
+```
+[manual.vpn.server_ip]
+[advanced.dns.server_ip]
+```
+Indeed the real variable name is server_ip and here you have a conflict.
+
+## Panels, sections and questions properties
+See [the full list of questions types and properties](/dev/forms)
+
+
+## Read and write values
+You can read and write values with 2 mechanisms: the `bind` property in the `config_panel.toml` and for complex use cases the getter/setter in a `config` script.
+
+### `bind` property
+The `bind` property allows to define where read and write the value bind to the question.
+
+#### Default behaviour
+
+If you have not defined a specific getter/setter (see bellow), and without `bind` argument it will read and save the value in app settings yaml file.
+
+#### Read / write into a var of a configuration file
+
+If you want to read and save the value into a variable (called like the option name) of a file (json, yaml, ini, php, py ...) you can do:
+
+```
+bind = ":__INSTALL_DIR__/config.yml"
+```
+
+If you want to read and save the value into an other variable than the `config_panel.toml` question short key (email in the example) of a file (json, yaml, ini, php, py ...) you can do:
+```
+bind = "email:__FINALPATH__/config.yml"
+```
+
+!!!! Note: This mechanism is quasi language agnostic, however it's monoline: you can't save multiline text or file in a variable with this method. If you need to save multiline content in a configuration variable, you should do it via a specific getter/setter.
+
+Sometimes, you want to read and save a value in a variable name that appears several time in the configuration file (for example variables called `max`). The `bind` property allows you to change the value on the variable following a regex in a the file:
+
+```
+bind = "importExportRateLimiting>max:__INSTALL_DIR__/conf.json"
+```
+
+#### Read / write an entire file
+
+If you have a question of type file or text you could want to save the content into a specific path on the system.
+```
+bind = "__INSTALL_DIR__/img/logo.png"
+```
+
+### Specific getter / setter
+Sometimes the `bind` mechanism is not enough:
+ * the config file format is not supported (e.g. xml, csv)
+ * the data is not contained in a config file (e.g. database, directory, web resources...)
+ * the data should be writen but not read (e.g. password)
+ * the data should be read but not writen (e.g. status information)
+ * we want to change other things than the value (e.g. the choices list of a select)
+ * the question answer contains several values to dispatch in several places
+ * and so on
+
+For all of those use cases, there are the specific getter or setter mechanism for a question !
+
+To create specific getter / setter, you first need to create a `config` script inside the `scripts` directory
+
+#### Getter
+
+A getter is a bash function called `getter_QUESTION_SHORT_KEY()` which returns data through stdout. 
+
+Returns could have 2 formats:
+ * a raw format, in this case the return is binded directly to the value of the question
+ * a yaml format, in this case you can rewrite several properties of your question (like the `style` of an `alert`, the list of `choices` of a `select`, etc.)
+
+[details summary="<i>Basic example : Get the login inside the first line of a file </i>" class="helper-card-subtitle text-muted"]
+scripts/config
+```
+get__login_user() {
+    if [ -s /etc/openvpn/keys/credentials ]
+    then
+        echo "$(sed -n 1p /etc/openvpn/keys/credentials)"
+    else
+        echo ""
+    fi
+}
+```
+
+config_panel.toml
+```
+[main.auth.login_user]
+ask = "Username"
+type = "string"
+```
+[/details]
+
+[details summary="<i>Advanced example 1 : Display a list of available plugins</i>" class="helper-card-subtitle text-muted"]
+scripts/config
+```
+get__plugins() {
+    echo "choices: [$(ls $install_dir/plugins/ | tr '\n' ',')]"
+}
+```
+
+config_panel.toml
+```
+        [main.plugins.plugins]
+        ask = "Plugin to activate"
+        type = "tags"
+        choices = []
+```
+[/details]
+
+[details summary="<i>Example 2 : Display the status of a VPN</i>" class="helper-card-subtitle text-muted"]
+scripts/config
+```
+get__status() {
+    if [ -f "/sys/class/net/tun0/operstate" ] && [ "$(cat /sys/class/net/tun0/operstate)" == "up" ]
+    then
+    cat << EOF
+style: success
+ask:
+  en: Your VPN is running :)
+EOF
+    else
+    cat << EOF
+style: danger
+ask:
+  en: Your VPN is down
+EOF
+    fi
+}
+```
+
+config_panel.toml
+```
+        [main.cube.status]
+        ask = "Custom getter alert"
+        type = "alert"
+        style = "info"
+        bind = "null" # no behaviour on
+```
+[/details]
+
+#### Setter
+
+A setter is a bash function called `setter_QUESTION()`. This function could access new values defined by the users by using bash variable with the same name as the short key of a question.
+
+You probably should use `ynh_print_info` in order to display info for user about change that has been made to help them to understand a bit what's going.
+
+[details summary="<i>Basic example : Set the login into the first line of a file </i>" class="helper-card-subtitle text-muted"]
+scripts/config
+```
+set__login_user() {
+    if [ -z "${login_user}" ]
+    then
+        echo "${login_user}" > /etc/openvpn/keys/credentials
+        ynh_print_info "The user login has been registered in /etc/openvpn/keys/credentials"
+    fi
+}
+```
+
+config_panel.toml
+```
+[main.auth.login_user]
+ask = "Username"
+type = "string"
+```
+[/details]
+
+## Validation
+You will often need to validate data answered by the user before to save it somewhere.
+
+Validation can be made with regex through `pattern` argument
+```
+        pattern.regexp = '^.+@.+$'
+        pattern.error = 'An email is required for this field'
+```
+
+You can also restrict several types with a choices list.
+```
+        choices.option1 = "Plop1"
+        choices.option2 = "Plop2"
+        choices.option3 = "Plop3"
+```
+
+Some other type specific argument exist like
+| type | validation arguments |
+| -----  | --------------------------- |
+| `number`, `range` | `min`, `max`, `step` |
+| `file` | `accept` |
+| `tags` | `limit` |
+| `boolean` | `yes` `no` |
+
+Finally, if you need specific or multi variable validation, you can use custom validators function:
+```
+validate__login_user() {
+    if [[ "${#login_user}" -lt 4 ]]; then echo 'Too short user login'; fi
+}
+```
+
+## Other actions than read, validate and save
+
+### Restart a service at the end
+
+You can use the services key to specify which service need to be reloaded or restarted
+
+```
+services = [ 'nginx', '__APP__' ]
+```
+
+This argument could be on panel, section, or question.
+
+### Overwrite config panel mechanism
+
+All main configuration helpers are overwritable, example:
+
+```
+ynh_app_config_apply() {
+
+    # Stop vpn client
+    touch /tmp/.ynh-vpnclient-stopped
+    systemctl stop ynh-vpnclient
+
+    _ynh_app_config_apply
+
+    # Start vpn client
+    systemctl start ynh-vpnclient
+    rm -f /tmp/.ynh-vpnclient-stopped
+
+}
+```
+
+List of main configuration helpers
+ * ynh_app_config_get
+ * ynh_app_config_show
+ * ynh_app_config_validate
+ * ynh_app_config_apply
+ * ynh_app_config_run
+
+More info on this could be found by reading [vpnclient_ynh config script](https://github.com/YunoHost-Apps/vpnclient_ynh/blob/master/scripts/config)
diff --git a/pages/06.contribute/15.dev/03.forms/forms.md b/pages/06.contribute/15.dev/03.forms/forms.md
new file mode 100644
index 00000000..1781565c
--- /dev/null
+++ b/pages/06.contribute/15.dev/03.forms/forms.md
@@ -0,0 +1,139 @@
+---
+title: Forms
+template: docs
+taxonomy:
+    category: docs
+routes:
+  default: '/dev/forms'
+---
+
+# Forms
+
+YunoHost uses a lot of forms. You can found here information on supported types question and properties.
+
+## Questions
+!!! Questions are called `Options` in the code.
+
+### Generic properties
+
+| Property | Scope        | Description | Example |
+|----------|--------------|-------------|---------|
+| `type`   | Everywhere   | Specify the type of the question (see bellow for the list) | |
+| `ask`    | Everywhere   | The title of the question            | `ask.en = "Cats or dogs ?"` | 
+| `help`    | Everywhere  | An help message            | `help.en = "Think carefully!"` |
+| `optional`| Everywhere  | Set true if the question is not mandatory  | `optional = true` |
+| `readonly`| Everywhere  | Avoid user to be able to change the value | `readonly = true` |
+| `example` | Everywhere  | Give an example to help to understand the format of the answer||
+| `pattern.regexp` | Everywhere  | Regex to validate the new value||
+| `pattern.error` | Everywhere  | Error to display if the pattern doesn't match ||
+| `redact` | Everywhere  | Avoid a confidential value to be logged | `redact = true` |
+| `default` | Install     | A default value for the question            | |
+| `visible` | ConfigPanel | A simple js expression based on other short keys questions to hide or display dynamically the question| `visible = "login && ! private_key"` |
+| `bind` | AppConfigPanel | See [App configuration panel doc](/packaging_config_panels) |
+
+ * `help`, `optional`, `readonly` and `visible` are also available on panels and sections entities.
+ *  Long help messages could not to be correctly displayed for user using yunohost CLI
+ * For the moment `default` properties are not supported in app config panel and you have to initialize the value by yourself in config file or settings.
+
+
+### `display_text` (readonly)
+Display a simple text.
+
+### `markdown` (readonly)
+Display a markdown (if you don't use markdown features, prefer display_text)
+
+### `alert` (readonly)
+Display an alert box with different style.
+
+| Property | Description  | Default |
+|----------|--------------|---------|
+| `style`    | Style of the alert box (success, info, warning, danger) | info |
+
+### `button`
+Display a button with different style (useful for custom actions).
+
+| Property | Description  | Default |
+|----------|--------------|---------|
+| `style`    | Style of the alert box (success, info, warning, danger) | success|
+| `enabled`    | Enable or disable the button | True        |
+
+### `string`
+Input text monoline.
+
+### `text`
+Input text multilines
+
+| Property | Description  | Default |
+|----------|--------------|---------|
+| `redact`    | Style of the alert box (success, info, warning, danger) | success|
+
+### `password`
+Password input. `{}` chars are forbidden and value is not added to logs.
+
+### `color`
+Hexadecimal color starting with # with a color picker.
+
+### `number`
+An integer.
+
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `min`    | Minimal value             |         |
+| `max`    | Maximum value |         |
+| `step`   | Steps between each next possible value |         |
+
+### `range`
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `min`    | Minimal value             |         |
+| `max`    | Maximum value |         |
+| `step`   | Steps between each next possible value |         |
+
+### `boolean`
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `yes`    |              |         |
+| `no`     |              |         |
+
+### `date`
+A date picker with date in the format YYYY-MM-DD
+
+### `time`
+A time picker
+
+### `email`
+An email input
+
+### `path`
+### `url`
+By default it ask for a web URL but you can change the `pattern` if you want to.
+
+### `file`
+File question
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `accept`    | Same format than HTML file input |         |
+
+! This file type is not made for big files transfer, it's just for small logo, or config files.
+
+### `select`
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `choices`  | list or dictionary of choices |         |
+
+### `tags`
+| Property | Description  | Example |
+|----------|--------------|---------|
+| `choices` | List or dictionary of choices |        |
+
+### `domain`
+List all added domains
+
+### `app`
+List all installed apps
+
+### `user`
+List all users
+
+### `group`
+List all groups