# Preview & Live Log URL: https://docs.ablyft.com/developers/debugging/preview-and-live-log/ > Debug mode, preview mode, the QA tool, forced variations and the Live Log. This page describes the tools that show you what ABlyft does on a page and which events it sends. | Tool | Use it to | | --------------------------------------- | ---------------------------------------------------------- | | [Debug mode](#debug-mode) | See in the console why experiments run or do not run | | [Preview mode](#preview-mode) | Look at a variation without being part of the real traffic | | [QA tool](#qa-tool) | Check targeting and goals while you click through the site | | [Force a variation](#force-a-variation) | Show a specific variation from your own code | | [Live Log](#live-log) | See the events that ABlyft really received | ## Debug mode Debug mode writes the decisions of the snippet to the browser console. Each line starts with `ABlyft #`. ### Turn it on 1. Open your project and go to **Settings → Project Settings**. 2. In the section **Debug Mode**, enable **Debug mode**. 3. Optionally enable **Restrict debug mode**. Then only browsers that opened a page with `?ablyft_show_debug=true` show the output. The setting is remembered for the browser session. 4. Save and wait for the [publication](https://docs.ablyft.com/developers/installation/publishing/). > **Debug mode switches itself off:** Debug mode turns off automatically after 8 hours, and it turns off snippet caching while it is on. Do not leave it on > for longer than needed, and use **Restrict debug mode** on a live website so that visitors do not see console output. ### What you see With debug mode on, the console shows the initialization of the snippet (project, revision, storage) and then one line per decision, indented by level: * `Initiated PAGE "…"`: a page matched and became active * `Initiated EXPERIMENT "…"`, `Initiated ENVIRONMENTS LOOKUP`, `Initiated AUDIENCES LOOKUP`: the experiment is being checked * `ENVIRONMENT "…" is matching`, `AUDIENCES passed`, `Passed all exclusion groups`, `Exclusion group not passed` * `EXPERIMENT "…" not running - User is excluded`: the visitor has been excluded before and stays excluded * `Triggering BUCKETING Event`: the visitor was assigned to a variation * `Applying JS`, `Applying VisualChanges`: variation code is run * `Triggered GOAL "…"`: a goal fired * `General Prerequisite Rules NOT met`, `Tracking Prerequisite Rules NOT met`, `Rated as Bot- Exiting`: the snippet stops or does not track Errors in rules or in your JavaScript are shown as `ERROR on …` in red and are also dispatched as the browser event `ablyftError`, see [Verify the integration](https://docs.ablyft.com/developers/debugging/verify-integration/#6-react-to-snippet-events-in-your-code). ## Preview mode Preview mode lets you look at a variation of an experiment, even if the experiment is not running yet. The easiest way is the **Preview** section on the experiment page. Select a **Variation to preview** and a **URL to preview**, and open the link **Open preview directly in browser**. You can also copy the **Preview/Sharing URL** or scan the QR code to preview on a phone. See [Preview & QA](https://docs.ablyft.com/guides/experiments/preview-and-qa/). Behind the scenes, the preview link contains the URL parameters `ablyft_preview` and `ablyft_exclude_running`, see [URL parameters](https://docs.ablyft.com/developers/reference/url-parameters/#ablyft_preview). The settings are kept for the browser session (in `sessionStorage`), so you can click through your website without repeating the parameters. Which experiments and checks apply during a preview is described in [Preview & QA](https://docs.ablyft.com/guides/experiments/preview-and-qa/#the-preview-box). Triggered goals are not sent, but recorded locally, see below. Check the state of preview mode in the console: ```js ablyft.get('data').isPreview; // true in preview mode ablyft.get('preview_bucketing'); // { experimentId: variationId } from the preview parameter ablyft.get('pingedGoals'); // goals that fired in preview mode: [{ id, time, value }] ``` > `pingedGoals` is filled in preview mode only. It lists goals that were triggered in the current browser session, which > makes it a quick way to test goals without touching your results. To leave preview mode, close the tab, or delete the session storage keys starting with `ablyft_` (`ablyft_preview_combs`, `ablyft_exclude_running`). ## QA tool The QA tool shows a panel on top of your website while you browse it in preview mode. It helps you check targeting and goals. 1. Open the experiment and go to the **Preview** section. 2. Click **Open with quality assurance tool**. This opens your page with the additional parameter `ablyft_qa_token=`. The snippet loads the tool after the page has loaded and keeps the token for the browser session. > **Allow the QA tool in your site:** If your site uses a Content Security Policy, `app.ablyft.com` must be allowed in `connect-src` for the QA tool. See > [Network and Content Security Policy](https://docs.ablyft.com/developers/installation/requirements/#network-and-content-security-policy). ## Force a variation To show a specific variation to a visitor from your own code, for example in an automated test, push a `forceVariation` event, see [`ablyft.push()`](https://docs.ablyft.com/developers/reference/javascript-api/push/#forcevariation) for the call and its limits. Forced visitors are real participants, for a quick look at a variation use [preview mode](#preview-mode). ## Opt out for testers To keep your own visits out of the data, open your website once with `?ablyft_opt_out=true`. See [Opt out](https://docs.ablyft.com/developers/consent-and-security/storage-and-privacy/#opt-out). ## Live Log The **Live Log** (**Project → Activity Log → Live Log**) shows the latest events that ABlyft received from the snippets of your project. Columns, filters and how to read them are described in [Check events in the Live Log](https://docs.ablyft.com/guides/goals-and-measurement/verify-measurement/#check-events-in-the-live-log). > Goals triggered in [preview mode](#preview-mode) are not sent, so they do not appear in the Live Log. ## Next steps * [Verify the integration](https://docs.ablyft.com/developers/debugging/verify-integration/) * [Common issues](https://docs.ablyft.com/developers/debugging/common-issues/) * [URL parameters](https://docs.ablyft.com/developers/reference/url-parameters/)