Android app

Holdfast

Holdfast is a personal blocker for adult content. Filtering runs on the phone: a local VPN answers DNS for blocked names and can point Google, YouTube, Bing, and DuckDuckGo at their restricted search modes. HTTPS is not decrypted. Browsing history is not uploaded.

What it does

Blocks adult domains from lists kept on the phone. An allowlist lets you keep a domain you still need.
Can also block a short malware-and-ads domain list, and known VPN, DNS-over-HTTPS, and downloader domains, while protection is on.
Uses an Accessibility service, while protection is on, to watch selected social apps and browsers for an explicit label or search, then leave that screen. The partner can see the app or site name and the time, not the words.
Can be a device admin so Android blocks uninstall until a partner allows it. It does not lock the screen, change the phone PIN, or erase the phone.
Offers an optional screen check. When you turn it on, Holdfast captures a small image of the screen and asks the pairing service whether it should block. The image is not kept as a photo album, and the partner does not receive the image.
Pairs with a person you choose. That partner can approve a 1-hour unlock, a 24-hour unlock, an indefinite pause, uninstall, or a partner change. You can lock protection back on yourself.
Can send that partner a daily or weekly report of protection time, time unlocked, requests, and interruptions. Content-block counts and app or site labels are included when history sharing is on.
Includes a Bible study screen, and points to Steadfast for a fuller reading library.

Sign-in and Plus

Pairing uses an email and password. Holdfast Plus is an optional Google Play subscription. Payment is handled by Google Play. The app does not show third-party ads.

Holdfast asks you to confirm that you are 18 or older before you continue. That yes or no stays on the phone.