This is just a list of them, but hopefully you can get an idea of what’s possible. At the moment you need to look at the source code to know exactly what each of these actions and filters do.

Actions

do_action("simple_fields_options_print_nav_tabs", $subpage);
do_action("simple_fields_subpage", $subpage);
do_action("simple_fields_init", $this);
do_action("simple_fields_register_field_types");
do_action("simple_fields_settings_admin_head");
do_action("simple_fields_enqueue_scripts", $this);
do_action("admin_print_footer_scripts");
do_action("simple_fields_admin_head", $this);
do_action("simple_fields_clear_caches");
do_action("simple_fields_options_page_save", $action);
do_action("simple_fields_after_last_options_nav_tab", $subpage);

Filters

apply_filters("set_post_connector_from_template", $connector_to_use, $post);
apply_filters("get_post_connector_from_template", $post_connector, $template);
apply_filters( "simple_fields_debug_output", $out )
apply_filters( "simple_fields_get_post_value", $return_val, $post_id, $field_name_or_id, $single)
apply_filters( "simple_fields_get_post_group_values", array(), $post_id, $field_group_name_or_id, $use_name, $return_format)
apply_filters( "simple_fields_get_all_fields_and_values_for_post", $selected_post_connector, $post_id, $args)
apply_filters('the_category', $category->name ))
apply_filters( "simple_fields_get_meta_query", $query_args, $group_id, $field_id, $value, $compare, $type, $order, $num_in_set)
apply_filters( "simple_fields_query_posts", $query_args)
apply_filters( "simple_fields_value", $value, $field_slug, $post_id, $options)
apply_filters( "simple_fields_values", $arr_comma_slugs_values, $field_slug, $post_id, $options)
apply_filters("simple-fields-return-values-" . $one_field_group_field["type"], $saved_values)
apply_filters( "simple_fields_connector", $return_val, $post_id)
apply_filters( "simple_fields_fieldgroup", $values, $field_group_id_or_slug, $post_id, $options)
apply_filters( "simple_fields_get_slug_pattern", $pattern)
apply_filters( "simple_fields_get_default_connector_for_post_type", $selected_post_type_default, $post_type )
apply_filters("simple_fields_save_postdata_do_wpautop", $do_wpautop, $post_id)
apply_filters("simple_fields_add_post_edit_side_field_settings", true, $post)
apply_filters( "simple_fields_get_post_type_defaults", $post_type_defaults )
apply_filters( "simple_fields_get_field_groups", $field_groups )
apply_filters( "simple_fields_get_field_group", $return )
apply_filters( "simple_fields_get_field_in_group", $return, $field_group, $field_id)
apply_filters( "simple_fields_get_selected_connector_for_post", $connector_to_use, $post)
apply_filters( "simple_fields_get_pages_args", $args)
apply_filters( "simple_fields_get_pages_output", $output, $args)
apply_filters("simple-fields-add-admin-menu", $show_submenu_page)
apply_filters( "simple_fields_get_post_connectors_for_post_type", $arr_found_connectors, $post_type)
apply_filters( "simple_fields_get_options", $options)
apply_filters( "simple_fields_save_options", $new_options)
apply_filters( "simple_fields_get_extended_return_values_for_field", $return_field_value, $field, $field_value)
apply_filters( "simple_fields_get_field_group_by_slug", $one_field_group, $field_group_slug)
apply_filters("simple_fields_get_meta_key_num_added_template", $custom_field_key_template)
apply_filters("simple_fields_get_meta_key_num_added", $custom_field_key)
apply_filters("simple_fields_get_meta_key_template", $custom_field_key_template)
apply_filters("simple_fields_get_meta_key", $custom_field_key)
apply_filters( "simple_fields_get_field_by_slug", $one_field, $field_slug, $fieldgroup_slug)
apply_filters("simple_fields_get_html_text_types", $arr_text_input_types)