Samer Azzam has Stackables (iTunes Link) for the iPhone, iPod Touch, and iPad in the iTunes App Store for FREE (regularly $2.99) for a limited time.

Stackables is the most advanced and comprehensive effects layering and blending app. It’s packed with over 200 effects expertly crafted by renowned photographer Dirk Wuestenhagen. These include tasteful textures, light leaks, emulsion, grit and grain, analog film filters, vintage gradients, elaborate geometric patterns, and much more.

In addition, Stackables comes equipped with over 20 professional adjustment tools most notably White Balance, Color Balance, Vignette, Sepia, Grain, Blur, Tilt Shift, and Depth of Field. And for the first time ever on a mobile device, these tools are added as layers, giving you unprecedented control over color and tonal levels in your composition.

Stackables’ layers-based architecture and nondestructive workflow encourage experimentation and foster creativity. Add layers to your heart’s content and see impressive results with every new layer. Have peace of mind in knowing that all edits are completely modifiable and reversible regardless of when you’ve done them in your editing process.

Usher in a whole new world of creative possibilities with advanced masking tools. Whether used to partially apply effects or as building blocks in abstract art constructions, masks are an indispensable part of any workflow. Choose from dozens of gradient and geometric masks and enjoy unprecedented creative freedom and control.

Instantly transform your photos into works of art with 30 preset formulas meticulously constructed by Dirk. Explore dozens of user-created formulas hand-picked from hundreds of submissions. Or save your own edits as formulas and never lose a custom edit you love. And with our proprietary social editing platform, you can share your formulas with friends via email or transfer them between your devices.

With its revolutionary design, easy to navigate interface, and streamlined workflow, Stackables is perfect for any skill level. Whether you’re an avid photographer or an aspiring enthusiast, Stackables provides you with the tools you need to elevate your mobile artistry.

Readdle has PDF Expert 5 (iTunes Link) for the iPhone, iPod Touch, iPad in the iTunes App Store for FREE (regularly $9.99) for a limited time.

PDF Expert 5 is a must-have app for anyone who reads, annotates or edits PDF documents on iPad or iPhone. It allows you to mark up documents with highlights and handwriting, insert text and stamps, sign and even merge PDFs. Moreover, PDF Expert 5 is the best choice for filling out PDF forms right on your iPad and iPhone.

You can open various file formats such as iWork, MS Office, PowerPoint, text files, images, even music and video files, etc. Get these files from desktop computers, email attachments, documents on Dropbox, OneDrive, GoogleDocs and “Open in” from other applications.

PDF Expert 5 provides the best experience for filling out PDF forms. Text fields, checkboxes, radio buttons and other form elements work as you expect and all the information you enter is saved within the form. Even complex interactive forms with Javascript work impressively well.