1. Purpose and Scope
1.1. Definitions
“Support” of browsers and operating systems is defined as:
- The system can be accessed using the given browser and operating system combination.
- Reported issues will be triaged and addressed following our internal Standard Operating Procedures.
1.2. Purpose
Castor is committed to providing a secure, seamless and high-performance experience across its product portfolio, including Castor CDMS and Castor eConsent. This policy outlines the supported web browsers and operating systems (OS) for both:
- Participant-facing functionalities (non-system users)
- Clinician-facing functionalities (system users)
The objective of this policy is to define the set of browser/OS combinations which Castor is committed to supporting that will ensure:
- Compatibility and accessibility across a wide range of devices
- Data security and integrity in compliance with industry and regulatory standards
- Optimal performance and usability for all users
Note: If users access Castor products with an unsupported browser/OS combination they will be directed to upgrade their browser to a supported version, or to an alternate mainstream browser that is readily available on their device.
1.3. Scope
Participant-facing functionality includes:
Any views or interactions participants engage with on Castor’s platform such as:
- Online surveys, questionnaires, informed consent forms
- Patient-reported outcomes (ePROs)
- Televisit functionality
Clinician-facing functionality includes:
Any views or interactions study users engage with on Castor’s platform such as:
- Data entry, review, and monitoring
- Study management and reporting tools
- Administrative functions used by study staff
Note: Castor Connect is excluded from this policy and the associated device/OS support details can be found under the latest Castor Connect Release – System Requirements Document.
1.4. Policy review frequency & communication
This policy will be reviewed and updated annually (every 12 months) or sooner to address vendor updates, changes in browser release cadence, security vulnerabilities, or performance and compatibility issues. Updates are guided by Castor’s goal of ensuring at least 95% user coverage, allowing access through the installation or upgrade of supported browser versions. To determine which browsers and operating systems remain supported, Castor relies on market share data and internal usage logs for such analysis.
The up-to-date version of this policy will be published online. To access this policy please visit helpdesk.castoredc.com or contact [email protected].
All users will be able to regularly review a comprehensive list of supported and validated version numbers via the product release notes that accompany each major product update.
2. Supported Web Browsers
In line with this commitment, Castor supports the following browsers:
2.1. Participant-Facing functionality
2.1.1. Chromium-Based Browsers
- Google Chrome: Latest 12 major versions
- Microsoft Edge: Latest 12 major versions
- Samsung Internet Browser: Current major version
Note: While users may access the system via other Chromium-based browsers, performance and security are not guaranteed.
2.1.2. Non-Chromium-Based Browsers
- Safari (iOS, iPadOS, macOS) (WebKit-based): Current and previous major version
- Firefox (Gecko-based): Latest 12 major versions for desktop only.
- Note: While users may access the system via Firefox on mobile, performance and security are not guaranteed.
2.2. Clinician-facing functionality
2.2.1. Chromium-Based Browsers
- Google Chrome: Latest 12 major versions
- Microsoft Edge: Latest 12 major versions
2.2.2. Non-Chromium-Based Browsers
- Firefox: Latest 12 major versions
- Safari (iOS, iPadOS, macOS): Current and previous major version
Note: A detailed list of validated browser versions is included in the release notes of each major product update, accessible at helpdesk.castoredc.com. Newly released browser versions are assumed to be forward compatible and will be usable to access Castor systems. Clinician-facing views do not require mobile support, but some pages are optimized for tablet/mobile usage
3. Supported Operating Systems
Castor supports the following operating systems and discontinues support for any OS no longer maintained by its provider.
3.1. Participant-facing functionality (web & mobile)
Desktop OS (Web)
- Windows: Current and previous major version (versions still supported by Microsoft)
- macOS: Current and previous major version
Mobile OS (Web and Native Browsers)
- iOS/iPadOS: Current and previous major version
- iOS/iPadOS enforces its WebKit renderer on all browsers in its ecosystem.
- Android: Latest four major versions
3.2. Clinician-facing functionality (web only)
Desktop OS (Web)
- Windows: Current and previous major version (versions still supported by Microsoft)
- macOS: Current and previous major version
Mobile OS (Web and Native Browsers)
- iOS/iPadOS: Current and previous major version
- iOS/iPadOS enforces its WebKit renderer on all browsers in its ecosystem.
- Android: Latest four major versions
Note: Castor does not offer full mobile support, but some pages have been optimized for tablet/mobile usage.
OS Detection Limitations
In rare cases where a user’s operating system cannot be reliably detected, such as with certain combinations of Firefox or Safari on Windows and macOS, Castor will apply the most lenient version of the policy rules. This means affected users may not receive an upgrade prompt and will not be blocked from accessing the system, even if their OS version would otherwise be unsupported. This approach ensures consistent access without unintended disruption, particularly for participant-facing scenarios.
4. Outdated and unsupported browsers and OS
4.1. End-of-Life (EOL) browsers and OS
When a browser, browser version, or operating system reaches end-of-life (EOL) per its vendor’s policy, it will be removed from Castor’s supported list.
4.2. Outdated browser & OS versions
Users will receive a warning when their browser version has reached end-of-support, as per this policy.
- End-of-Support Notification: When the version used is officially unsupported, users will be prompted to update their browser. Access to the system will be restricted until an update is performed.
4.3. Unsupported browsers and OS
For any browsers and/or OS not listed in this policy, Castor will prevent access to the system. Users will receive a message instructing them to switch to a supported browser or OS.
In some cases, versions that fall outside the supported range may still be functional, but Castor does not guarantee performance, security, or full feature availability. Users are strongly encouraged to upgrade to a supported version for an optimal experience.
Note: Linux OS Exception Policy
Linux-based operating systems will be included as a standing exception to the CDMS OS allowlist, primarily to support development use cases (e.g. support rotations, on-call duties) and advanced study users but Castor does not guarantee performance, security, or full feature availability.
5. Revision History
Version 1.0 | Initial Release