In this page we document tweak changes and improvements per release version.


A bug fix and some improvements on expanding support of existent functionalities.

  • Announcement: tweak is now available on Firefox 🎉
  • Bug fix: Fix glitch in URL input field, was below the regular expressions toggle.
  • Feature: Partial support for iframes. Users are now able to intercept HTTP requests from iframes. The support we introduce is limited, the user needs to ensure he/she disables and re-enables the extension for tweak to attempt to kick into the iframes.
  • Feature: Proper support for non JSON formats. Provide different editor for users to manage non-JSON response payloads. Additionally allow users to setup mocks with invalid JSON.


We're happy to announce tweak 1.0! After improving the foundations of tweak in the initial releases where we mainly focus on making sure the extension intercepts requests consistently across different websites and different environments, we decided that now is the right time to focus on new features and enhancing user experience. We scanned the extensions in the market, and we cross-referenced dozens of browser extensions and their hundreds of reviews to come up with the feature set of this version. We then re-designed from scratch the extension UI focusing on productivity and usability, and we add a few other neat functionalities to provide you with a sound experience.

  • Feature: Allow users to delay a request by a specified amount of time.
  • Feature: Add a new action on the top bar to collapse all the expanded rows in the extension.
  • Feature: Add a new action on the top bar that allows users to delete all the configurations in one go.
  • Feature: Allow users to specify the request payload (request body) for POST, PUT and PATCH requests. The user can edit the request payload by clicking the Request Payload tab in the editors area.
  • Feature: Allow users to specify the Content-Type response header.
  • Feature: Allow users to specify the HTTP response status code of an intercepted request.
  • Enhancement: Overall extension re-design with major UI improvements. Some highlights:
    • Larger URL field (old URL match expression) with a new regular expression toggle and instant input validation.
    • Better interception count experience with improved active/inactive states. From this version on, the interception counter is always visible even when its value is 0. The team hopes that this serves as an indicator/call to action in cases where user is expecting an interception but does not get the expected result or neither feedback from the extension.
    • Larger and slightly more spacious JSON editor(s) with comprehensive footnote captions, to hint users towards the right direction when filling in the content based on the type of request their trying to intercept.
  • Feature: allow users to bypass requests despite the original one not being successful (e.g. status 404 or 500 are the most common use cases). Users may now simulate calls to resources that don't exist on the server, or even create their own routes in the extension to truly simulate an API.
  • Bug fix: deleting individual configuration didn't stop the request from being intercepted in the background. This might cause zombie interceptions, where a request is still intercepted even tough the user deleted the configuration. In prior versions of tweak the user would have to refresh the page to get rid of the zombie interception.
  • Bug fix: compute the proper header Content-Length based on the user defined payload.
  • Maintenance: 3rd party security dependencies updates.


Although we didn't introduced new functionalities in this release, we did some foundational changes in the way that tweak interacts with your website in order to augment the coverage of scenarios where it can intercept requests. That's the reason why we also changed our user permissions from activeTab to host permissions, allowing us to fix the following fundamental issues:

  • Feature: tweak is now able to intercept requests that are fired/triggered at page load 🎉🎉🎉
  • Bug fix: tweak interceptions were flaky for applications using XMLHttpRequest methods:
  • Bug fix: Prior to this release tweak was not capable of intercepting requests to the same host when the configuration had an absolute path in the URL match expression field.
  • Bug fix: Prior this release calls to window.fetch with Request object could not be intercepted.
  • Bug fix: Bubble up errors that occur during window.fetch. tweak was silencing these errors, which would make developer's job of debugging the request failure harder. In this new release, tweak properly surfaces the error to the application.


  • Feature: By default turn on the request interception switch toggle when adding a new configuration.
  • Feature: Notify users about number of intercepted requests by adding a badge counter to the extension icon.
  • Feature: Add a Run&Stop button on the top bar of the extension for faster access when in need of enabling/disabling the extension globally.
  • Feature: Small visual improvements:
    • Small tooltip for the URL match expression configuration field to inform the user about advanced usage use cases with regular expressions.
    • Custom title for JSON editor present in each configuration.