Chromatica Mark II is currently free on the App Store. It provides manual camera controls, presets, histograms, object tracking, and other photography tools for iPhone/iPad/Apple Watch.
ABC - Wooden Words, a word puzzle game, is free to download on the App Store with optional in-app purchases for hints/wallpapers. The app's own description states "Game completely Free." No purchase required to play.
NasScale, an iPhone client for self-hosted Synology NAS users with built-in Tailscale connectivity, file management, remote media playback and download-client integration, shows as free on the US App Store — no in-app purchases listed. Other storefronts (e.g. Taiwan) still show a small paid price (~NT$30 / roughly $0.99), consistent with GOTD's claimed "$0.99, FREE TODAY" promotion.
Video to Frames－Extract Photo is currently free on the U.S. App Store. It lets you step through videos frame by frame and export individual or multiple frames as photos.
LineWatch+ helps theme park visitors check live ride wait times, compare nearby attractions, and plan around shorter lines. The app is free on the U.S. App Store, but it includes banner ads; a one-time $0.99 in-app purchase removes them.
World of Juice is currently free to download from Apple’s App Store for iPhone and iPad. The puzzle game includes ads, but there is no purchase or credit card required to claim the app.
Quill - Todo list is currently free to download from the U.S. App Store. It offers a widget-focused task list and has a separate $2.99 Pro Lifetime in-app purchase. The store does not specify which features require Pro.