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Password Manager Resources


The Password Manager Resources project exists so creators of password managers can collaborate on resources to make password management better for users. Resources currently consist of data, or "quirks", as well as code.

"Quirk" is a term from web browser development that refers to a website-specific, hard-coded behavior to work around an issue with a website that can't be fixed in a principled, universal way. In this project, it has the same meaning. Although ideally, the industry will work to eliminate the need for all of the quirks in this project, there's value in customizing behaviors to ensure better user experience. The current quirks are:

  • Password Rules: Rules to generate compatible passwords with websites' particular requirements.
  • Shared Credentials: Groups of websites known to use the same credential backend, which can be used to enhance suggested credentials to sign in to websites.
  • Change Password URLs: To drive the adoption of strong passwords, it's useful to be able to take users directly to websites' change password pages.
  • Websites Where 2FA Code is Appended to Password: Some websites use a two-factor authentication scheme where the user must append a generated code to their password when signing in.

Having password managers collaborate on these resources has three high-level benefits:

  1. By sharing resources, all password managers can improve their quality with less work than it'd take for any individual password manager to achieve the same effect.
  2. By publicly documenting website-specific behaviors, password managers can offer an incentive for websites to use standards or emerging standards to improve their compatibility with password managers; it's no fun to be called out on a list!
  3. By improving the quality of password managers, we improve user trust in them as a concept, which benefits everyone.

We encourage you to incorporate the data from this project into your password manager, but kindly ask that you please contribute any quirks you have back to the project so that all users of participating password managers can benefit from your discoveries and testing.

The Resources, In Detail

Password Rules

Many password managers generate strong, unique passwords for people so that they aren't tempted to create their passwords by hand, which leads to easily guessed and reused passwords. Every time a password manager generates a password that isn't compatible with a website, a person not only has a bad experience but a reason to be tempted to create their password. Compiling password rule quirks helps fewer people run into issues like these while also documenting that a service's password policy is too restrictive for people using password managers, which may incentivize the services to change.

The file quirks/password-rules.json contains a JSON object mapping domains to known good password rules for generating compatible passwords for use on that website. The Password Rules language is a human- and machine-readable way to concisely write and read the rules to generate a compatible password on a website. quirks/password-rules.json is the quirks version of the passwordRules attribute, which is currently an open WHATWG proposal and supported in Safari. The same language is part of native iOS application development API. If a website changes its password requirements to be general enough to not warrant quirks, or if it adopts the passwordRules attribute to accurately communicate its requirements to password managers and web browsers, it should be removed from this list.

When a domain is listed in quirks/password-rules.json, it means that that domain and all of its subdomains use the rule. For example, a rule for will match URLs on as well as * A rule for will match URLs on as well as *, but will not match other subdomains of such as

A rule that should only be applied to the exact domain stated as a key should have the exact-domain-match-only key set to a value of true. The absence of the exact-domain-match-only key means that it is false.

Password Rules Language Parser

An implementation of a parser for the Password Rules language that's written in JavaScript can be found in tools/PasswordRulesParser.js. It can be used as a reference implementation, interpreted in build systems to convert data/password-rules.json to an application-specific format, or interpreted at application runtime wherever it's possible to execute JavaScript (e.g. using the JavaScriptCore framework on Apple platforms).

A third-party parser implementation that's written in Rust is also available.

Shared Credentials

The files quirks/shared-credentials.json and quirks/shared-credentials-historical.json express relationships between groups of websites that share credentials. The -historical file describes such relationships that were valid in the past but either are not valid today or we don't have a high degree of confidence are valid today.

Information in quirks/shared-credentials.json can be used by password managers to offer contextually relevant accounts to users on, even if credentials were previously saved for This list should not be used as part of any user experience that releases user credentials to a website without the user's explicit review and consent. In general, saved credentials should only be suggested to users with site-bound scoping. This list is appropriate for allowing a credential saved for website A to appear on website B if the website the credential was saved for is clearly stated.

There are existing proposals to allow different domains to declare an affiliation with each other, which could be a way for websites to solve this problem themselves, given browser and password manager adoption of such a proposal. Until and perhaps beyond then, it is useful to have these groupings of websites to make password filling suggestions more useful.

Information in quirks/shared-credentials-historical.json can be used by password managers to suppress password reuse warnings across websites, given that website A and website B once were known to share credentials in the past.

The Contributing document goes into detail on the format of these files.

Change Password URLs

The file quirks/change-password-URLs.json contains a JSON object mapping domains to URLs where users can change their password. This is the quirks version of the Well Known URL for Changing Passwords. If a website adopts the Change Password URL, it should be removed from this list.

Websites Where 2FA Code is Appended to Password

The file quirks/websites-that-append-2fa-to-password.json contains a JSON array of domains which use a two-factor authentication scheme where the user must append a generated code to their password when signing in. This list of websites could be used to prevent auto-submission of signin forms, allowing the user to append the 2FA code without frustration. It can also be used to suppress prompting to update a saved password when the submitted password is prefixed by the already-stored password.


Please review how to contribute if you would like to submit a pull request.

Asking Questions and Discussing Ideas

If you have any questions you'd like to ask publicly, or ideas you'd like to discuss, please raise a GitHub issue or send a message in the project's Slack instance. Anyone participating in the project is welcome to join the Slack instance by emailing the project's maintainers at Apple and asking for an invitation. Please include your GitHub user name when you do this.

Project Maintenance

Project maintenance involves, but is not limited to, adding clarity to incoming issues and reviewing pull requests. Project maintainers can approve and merge pull requests. Reviewing a pull request involves judging that a proposed contribution follows the project's guidelines, as described by the guide to contributing. If you are interested in becoming a project maintainer, please email the project maintainers at Apple with the following information:

  • Your name
  • Your GitHub user name
  • Any organizations you're affiliated with that are related to password management, including professionally
  • Links to examples of pull requests submitted, review feedback given, and comments on issues that demonstrate why you'd be a good project maintainer

Ideally, you'd provide somewhere between five and eight examples. The purpose of this note is to remind the Apple maintainers of who you are; ideally, before sending this message, we already know you from your great contributions!

Project maintainers are expected to always follow the project's Code of Conduct, and help to model it for others.

Project Governance

Although we expect this to happen very infrequently, Apple reserves the right to make changes, including changes to data format and scope, to the project at any time.


A place for creators and users of password managers to collaborate on resources to make password management better.



Code of conduct





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