iOS 9 Apps with Split view/slide over and PIP

Lets keep a list of apps that take advantage of all the iOS 9 goodies such as:

- Split View: only possible on iPad Air 2, iPad mini4 and iPad Pro
- Slide Over: only possible on iPad Air, iPad Air 2, iPad mini 2, iPad mini 3 or iPad mini 4 and iPad Pro
- Picture in Picture (PiP): only possible on iPad Air, iPad Air 2, iPad mini 2, iPad mini 3 or iPad mini 4 and iPad Pro
- 3D Touch (Quick Actions, Peek and Pop, Pressure Sensitivity): only on iPhone 6s & 6s+
- Quick Reply for 3rd party apps | Check Settings app. How it works.
- Spotlight search in 3rd party apps
- App Thinning (app slicing) > see special wiki topic
- Deeplinks
- iPad Pro support

Slide Over/Split view in general unfortunately lacks:
1) open the app that you have open in Slide Over to change to main app (full screen)
2) search bar to search your favorite app (if it supports this feature)
3) deselect apps that you don't want to show in the list of apps that support Slide Over/Split view



This post is a wiki so please add any that you find!!! (Hint: it's alphabetically sorted)

Actionify: Slide Over / Split View
Adobe Photoshop Mix: Slide Over / Split View
Adobe Photoshop Fix: Slide Over / Split View
Adobe Creative Cloud: Slide Over / Split View
Adobe Comp CC: Slide Over / Split View
AG Drive: 3D Touch - game
Allthecooks - Share your recipes! Free Recipe App: Slide Over / Split View, Spotlight
Amazon Video: Slide Over / Split View, Picture in Picture (PiP), 3D Touch (Quick Actions)
Anylist: Slide Over / Split View
AutoCAD 360: Split View
B&H Photo, Video & Pro Audio: Slide Over / Split View
BBC iPlayer (UK Only): Picture in Picture (PiP), iPad Pro support
BeWeather 2 - Slide Over / Split View, 3D Touch (Quick Actions)
Billings Pro: Slide Over / Split View
Booking.com: Spotlight
Booklover: Slide Over / Split View, 3D Touch (Quick Actions)
Box: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Buzzfeed: Handoff, Spotlight
Byword: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Calculator for iPad Free: Slide Over / Split View
Calculator Pro for iPad - Standard and Scientific: Slide Over / Split View
Calendar Z: Slide Over / Split View
Calendars by Readdle: 3D Touch (Quick Actions)
Calendars 5: 3D Touch (Quick Actions)
Camera+: 3D Touch (Quick Actions)
CARROT Weather: 3D Touch (Quick Actions)
Chrome: Slide Over / Split View, Picture in Picture (PiP) - internet browser
Chronicle - Bill Management & Reminders: Slide Over / Split View
Clips - Copy and paste anywhere with widget and keyboard: Slide Over / Split View, 3D Touch (Quick Actions, Peek and Pop)
Cloud Baby Monitor ~ Unlimited Range Video Baby Monitor: Slide Over / Split View
CloudBeats Pro - Spotlight search
CloudMagic Email: 3D Touch (Quick Actions) - e-mail
Cnet: Picture in Picture (PIP)
Coda: Slide Over / Split View, 3D Touch (Quick Actions)
Collins COBUILD Advanced Dictionary of American English: Slide Over / Split View
Colordrop - Extract and explore colors: Slide Over / Split View
Contacts Journal CRM - Professional Relationships Manager for Customers, Clients and Sales: Slide Over / Split View, Spotlight
Copied: Slide Over / Split View, 3D Touch (Quick Actions, Peek and Pop)
Copyfeed - take control of your clipboard: Slide Over / Split View
Craftsy: Video Classes, Supplies and Kits: Slide Over / Split View, Picture in Picture (PIP)
Crossy Road: Slide Over, Split View
dailyme TV: Picture in Picture (PiP) - German app
Dailymotion: Picture in Picture, Spotlight, Deeplinks
Davka Hebrew Writer: Slide Over / Split View
Day One: 3D Touch (Quick Actions)
Digg: Slide over / Split View
Disney Movies Anywhere - Picture in Picture (PiP)
Dispatch: Email meets GTD with TextExpander snippets: Slide Over / Split View, Spotlight
Documents 5: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions, Peek and Pop), iPad Pro support
Documents Free: Spotlight, 3D Touch (Quick Actions)
Domino's Pizza Nederland: Slide Over / Split View - Dutch version
Dozzzer: Slide Over / Split View
Drafts 4 - Quickly Capture Notes, Share Anywhere: Slide Over / Split View, Spotlight, Wireless Keyboard Shortcuts
Dropbox: Spotlight, 3D Touch (Quick Actions, Peek and Pop)
Due — Reminders, Countdown Timers: Slide Over / Split View
Duet: ReplayKit (record a video of your game)
EarthCam - Webcams: Slide Over / Split View, 3D Touch (Quick Actions)
Edmodo: Slide Over / Split View
Endless Alphabet: 3D Touch - game
ESPN: Picture in Picture (PiP), Spotlight, 3D Touch (Quick Actions)
Evernote: Slide Over / Split View, Spotlight, 3D Touch (Quick actions, Peek and Pop)
Facebook - 3D Touch (Quick Actions)
Fantastical 2 for iPhone: 3D Touch (Quick Actions) - calendar
Fantastical 2 for iPad: Slide Over / Split View - calendar
Feedly: Slide Over / Split View, 3D Touch (Quick Actions)
FileBrowser: Slide Over / Split View, Picture in Picture (PiP)
FileBrowserLite: Picture in Picture (PiP)
File Manager by Mousavian: Slide Over / Split View, Spotlight
FileMaker Go 14: Slide Over / Split View
Flipboard: Spotlight Search
Flipp: Slide Over / Split View
FormConnect: Slide Over / Split View
ForScore: Slide Over / Split View
Friendly Plus with AdBlock: Slide Over / Split View
Friendly Social: Slide Over / Split View
Funda: Slide Over / Split View - Dutch realestate - still pretty buggy in Slide Over
Funny or Die: Slide Over / Split View, Picture in Picture (PiP), Spotlight, Universal links
Genius Sign - Annotate PDF Documents: Slide Over / Split View
Go Keyboard: 3D Touch (Quick Actions)
Google app: Slide Over / Split View, 3D Touch (Quick Actions)
Google Drive: Slide Over / Split View, Spotlight, 3D Touch (Quick actions)
Google Play Newsstand: Slide Over / Split View
Google Translate: Slide Over / Split View
Green Kitchen – healthy vegetarian recipes: Siri Search, Spotlight
GV Connect - Call & SMS for Google Voice: Slide Over / Split View, Spotlight
Handle: To-do List, Inbox, and Calendar Management all in one: Slide Over / Split View
HBO GO: Picture in Picture (PiP), Spotlight
HBO NOW: Picture in Picture (PiP), Spotlight
Heapo Clipboard: Slide Over / Split View
HipChat: Slide Over / Split View
Hootsuite: Slide Over / Split View
Hulu: Picture in Picture (PIP)
Human Anatomy Atlas – 3D Anatomical Model of the Human Body: Slide Over / Split View, Spotlight
Hyper: Best Daily Videos: Picture in Picture (PiP) - must have video app for iPad in my opinion! - you have to press the home button to get PiP (so works different then in other video apps).
iA Writer 3.0.1: Slide Over / Split View
iBank for iPad: Slide Over / Split View
iHotel – Hotel Search: Slide Over / Split View
IMDB: Deep Links, Spotlight, 3D Touch (Peek and Pop)
iMovie: Slide Over / Split View in Photos app extension
Instagram: 3D Touch (Quick Actions)
Instashare Air Drop - Slide Over / Split View, 3D Touch (Quick Actions)
jetAudio Music Player: Slide Over / Split View
Jumbo: Slide Over / Split View - Dutch supermarket
Keynote: Slide Over / Split View, Picture in Picture (PiP), 3D Touch
Instapaper: Slide Over / Split View
Launch Center Pro: 3D Touch (Quick Actions)
Launcher with Notifications: Slide Over / Split View, 3D Touch (Quick Actions, Peek and Pop)
Librairie - Ebook Cloud Reader for epub and mobi: Slide Over / Split View, Spotlight, App Thinning
Log My Day: Slide Over / Split View
Lucidchart - Diagram & Flowchart: Slide Over / Split View
MacID: Slide Over / Split View, Spotlight, App Thinning, 3D Touch (Quick Actions)
Magic Piano by Smule: 3D Touch
MailPilot 2: Slide Over / Split View
Marvis Music Player: Slide Over / Split View, 3D Touch, Spotlight
MeisterTask: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions, Peek and Pop)
Menstruation and Ovulation Calendar: Slide Over / Split View, 3D Touch (Quick Actions), Spotlight
Messenger: Slide Over / Split View, Quick Reply (doesn't work for everybody)
Microsoft Excel: Slide Over / Split View, Wireless Keyboard Shortcuts
Microsoft OneNote: Slide Over / Split View, Spotlight
Microsoft Outlook: Slide Over / Split View, Spotlight, Wireless Keyboard Shortcuts - e-mail
Microsoft PowerPoint: Slide Over / Split View, Wireless Keyboard Shortcuts
Microsoft Word: Slide Over / Split View, Wireless Keyboard Shortcuts
MindMeister: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions, Peek and Pop)
MindNode: Slide Over / Split View, Spotlight
MLB At Bat: Picture-in-Picture (PIP)
Moxtra - Slide Over / Split View, Spotlight
Music Launcher: Slide Over / Split View
My Folder 2: Slide Over / Split View, Spotlight
myMail: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions) - e-mail
My Verizon Mobile (US Only): Slide Over / Split View, Spotlight
Netflix: Picture in Picture (PiP)
Newsify: Slide Over / Split View
NOAA World Radar: Slide Over / Split View, Spotlight
NOAA World Radar Free: Slide Over / Split View, Spotlight
NPO Radio 1,2,3FM,4,5,6,FunX, Zappelin radio - Slide Over / Split View - Dutch public broadcaster apps
nPlayer: Slide Over / Split View, Picture in Picture (PiP) - Quick Time videos only
Numbers: Slide Over / Split View, Picture in Picture (PiP), 3D Touch
OmniFocus 2.8 (for iPhone): Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
OmniFocus 2.8 (for iOS): Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
OmniGraffle 2: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
OmniOutliner 2: Slide Over / Split View. Spotlight
OmniPlan 2: Slide Over / Split View
Onefootball: Slide Over / Split View, Spotlight
OnePad Pocket Notebook: Slide Over / Split View
Opener ‒ open links in apps: Slide Over / Split View
Overcast - Slide Over / Split View, 3D Touch (Quick Actions)
Pages: Slide Over / Split View, Picture in Picture (PiP), 3D Touch
Parcel - Delivery Tracking: Slide Over / Split View, Spotlight, Proactive within app, iOS 9 share extension
Paper: 3D Touch, iPad Pro support
PCalc - The Best Calculator: Split Screen / Slide Over
PCalc Lite - The Best Free Calculator: Split Screen / Slide Over
PDF Experts 5: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions, Peek and Pop), iPad Pro support
PDF Markup Ultimate - Annotate, Scan, Fill Forms, and Take Notes with PDF Reader: Slide Over / Split View
PDF Office: 3D Touch (Quick Actions)
Pingpad: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Pinterest: 3D Touch (Quick Actions)
Pixelmator: Slide Over / Split View
Plane Finder: Slide Over / Split View
Play video while using another App for YouTube - Moldavite: Picture in Picture (PIP) | YouTube player
Pleco Chinese Dictionary: Slide Over / Split View, 3D Touch
Plex - Picture in Picture (PiP)
Pocket: Picture in Picture (PiP), Spotlight
Pocket Informant: Slide Over / Split View, 3D Touch (Quick Actions, Peek and Pop)
Printer Pro: 3D Touch (Quick Actions)
ProTube for YouTube: Picture in Picture (PIP), Slide Over / Split View, 3D Touch (Quick Actions) | YouTube player
Puffin Browser Pro: Slide Over / Split View - internet browser
Quip - Docs, Chat, Spreadsheets: Slide Over / Split View, Spotlight, Wireless Keyboard Shortcuts
RTLXL: Picture in Picture (PiP) - Only possible with paid subscription (Dutch commercial tv station)
Runtastic: 3D Touch (Quick Actions)
Runtastic Pro: 3D Touch (Quick Actions)
Scanbot Document Scanner: Split Screen / Slide Over, Spotlight
Scanner Pro: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Screenshot++: Slide Over / Split View, Spotlight
Shazam: 3D Touch (Quick Actions)
Ship Finder: Slide Over / Split View
Shoot by ProCam: 3D Touch (Quick Actions)
Sidefari: Slide Over / Split View - Safari internet browser plugin to open two Safari instances
SignEasy - Sign and Fill Documents: Slide Over / Split View
Skype for iPhone: Quick Reply
Skype for iPad: Slide Over / Split View, Quick Reply
Slack: Slide Over / Split View
SLPRO: Slide Over / Split View
Smartsheet: Slide Over / Split View
SnipNotes: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Soriko Radio: Slide Over / Split View, App Thinning, SFSafariViewController, watchOS 2, Power Saving & Keyboard shortcuts
Soundrocket for SoundCloud: Slide Over / Split View
Spark: Spotlight, 3D Touch (Quick Actions, Peek and Pop) - e-mail
Star Walk ™ 2 - Guide to the Night Sky to Watch Stars, Planets, Meteor Showers & Constellations: Slide Over / Split View, Spotlight Search
SwiftKey Keyboard: Slide Over / Split View
Telegram: Slide Over / Split View, Quick Reply, 3D Touch (Quick Actions, Peek and Pop), Picture in Picture (PiP)
Terminology 3 - Extensible Dictionary and Thesaurus: Slide Over / Split View, Safari View Controller
TestFlight: App Thinning
Textilus Pro - Advanced word processing for iPad and iPhone: Slide Over / Split View
The Guardian: Slide Over / Split View, Spotlight and deep linking
The Huffington Post: Slide Over / Split View
The Night Sky: Slide Over / Split View, Spotlight, App Thinning, 3D Touch.
The Wisdom English Japanese 2: Slide Over / Split View
Theory Lessons: Slide Over / Split View, Deep Linking
Things: 3D Touch (Quick Actions)
Things for iPad: Slide Over / Split View
TileBrowser: Slide Over / Split View - internet browser - is missing cloud storage support
Timesheet - Time Tracker: Slide Over / Split View
Travel List – Trip Packing and Planning: Slide Over / Split View
Trello: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions)
Tweetbot 4 for Twitter: Slide Over / Split View, Quick Reply, 3D Touch (Quick Actions, Peek and Pop)
Twitch: Slide Over / Split View, Picture in Picture (PiP)
Twitter: Slide Over / Split View, Quick Reply
Twitterific 5: Slide Over / Split View, Quick Reply
USAA Mobile: Slide Over / Split View, Spotlight
uSurf Universal: Slide Over / Split View, iPad Pro support - internet browser
Vessel: Slide over / Split View / Picture in Picture (PiP)
VidOn - Slide Over / Split View
Vimeo: Slide over / Split View / Picture in Picture (PiP), Spotlight search
VLC for Mobile - Slide Over / Split View
VUDU - Picture in Picture, 3D Touch.
WatchBeam: Slide over / Split View, Picture in Picture (PiP)
WatchESPN: Picture in Picture (PiP)
Weather+: Slide Over / Split View
Weather Live: Slide Over / Split View
WeatherPro: Spotlight
Web TV for Chromecast - Slide over / Split View / Picture in Picture (PiP)
WebProtectMe Safe Browser with Parental Control: Slide Over / Split View - internet browser
WhatsApp - 3D Touch (Peek and Pop, Quick Actions), Quick Reply (only works in iOS 9.1 and later)
Wikipanion Plus for iPad: Slide Over / Split View
Wikipanion for iPad: Slide Over / Split View
Workflow: 3D Touch (Quick Actions), iPad Pro support
WPS Office: Slide over / Split View, Spotlight search, 3D Touch (Quick Actions), iPad Pro support
Wunderlist: Slide Over / Split View, 3D Touch (Quick Actions, Peek and Pop)
WWDC: Picture in Picture (PiP)
Yahoo Mail - Slide Over / Split View
YouPlayer: Picture in Picture (PIP), Slide Over / Split View | YouTube player
You Doodle: Slide Over / Split View
Zero: Slide Over / Split View
104 Days: The weekend calendar: Slide Over / Split View
1Password: Slide Over / Split View, Spotlight
1Writer: Slide Over / Split View, Spotlight
2Do: Slide Over / Split View, Spotlight, 3D Touch (Quick Actions, Peek and Pop)
500px - Discover photos from the world's best photography community: Slide Over / Split View

Other apps: Here is a real time search of apps with "split" in the update description.

Is it possible to have two apps open next to each other on older iPads (and iPhones)? yes*/**
I also found a few great apps that also have a split view option (left/right and/or top/bottom) which also works great on non iPad Air 2 and iPad mini4 and iPhones.

**On jailbroken iDevices you can use 'Medusa' to use a Split view / Slide over or Picture in picture feature on older iDevices see instructions here.

*On non-jailbroken iDevices you can use below apps. Please note that these apps do not use the Split view option which Apple build in since iOS9. These are simply apps which have two browser windows next to each other. I haven't tried YouTube videos yet within such a browser to see if you can also have a PiP window aside from the two browsers on e.g. an iPad mini2.

Internet browsers:
uSurf Universal (free) | requires iOS8 or later (also supports Apple's Slide over/Split view and supports iPad Pro) | also works on iPhone Tip
Split Screen Browser (free) | requires iOS7 or later | iPad only
Split Web Browser (free) | requires iOS6 or later | also works on iPhone
Browse and Tube / Browse and Tube Free | requires iOS4.3 or later | iPad only
CoSurf (free) | requires iOS8 or later | also works on iPhone
Split (1,99 dollar) | requires iOS7 or later | also works on iPhone
Split Screen MultiTasking (free) | requires iOS8 or later | also works on iPhone
twoBrowser (free) | requires iOS6 or later | also works on iPhone
dualBrowser (free) | requires iOS7 or later | also works on iPhone
Split Screen Browser Pro (0,99 dollar) / Split Screen Browser (free) | requires iOS7 or later | iPad only
2in1 (4,99 dollar) | requires iOS6 or later | also works on iPhone

Internet browser and other features:
Split (1,99 dollar) | requires iOS7 or later | also works on iPhone
Twistext (0,99 dollar) | requires iOS6.1 or later | also works on iPhone
Side by Side (free) | Side by Side Pro (1,99 dollar) | requires iOS5 or later | iPad only
Skipper (0,99 dollar) | requires iOS3.2 or later | iPad only
Split Pea (1,99 dollar) | requires iOS6.1 or later | iPad only - currently crashes on iPad mini2 running 9.1
PaperHelper (0,99 dollar) | requires iOS7 or later | iPad only |
Photon Flash Browser (9,99 dollar - temporary 4,99 dollar) | requires iOS5.1.1 or later | iPad only

Documents:
Easy Annotate (free, with in-app purchase 4,99 dollar) | requires iOS8 or later | also works on iPhone - Websites + PDF viewing and minor notes only, supports iCloud Drive, Dropbox, Google Drive (only in paid version) TIP!
Side by Side (free) | Side by Side Pro (1,99 dollar) | requires iOS5 or later | iPad only - Websites + PDF viewing only, supports Dropbox, Google Drive, iCloud
Dual PDF (free) | requires iOS8.1 or later | also works on iPhone - PDF viewing only, supports Dropbox, Google Drive, iCloud TIP!
Dual Documents Viewer (1,99 dollar) | requires iOS6 or later | iPad only - Italian language (only), supports PDF,DOC(X),XLS(X),TXT,EPS,PSD, only viewing top/bottom (not left/right), supports Dropbox TIP!
TileBrowser (7,99 dollar) | requires iOS7.1 or later (also supports Apple's Slide over/Split view) | also works on iPhone | iWork, Microsoft Office 97 or newer, RTF, PDF, TXT, CSV - is missing cloud storage support

Screenshot of Easy Annotate:

 

A screenshot of night sky split view

 

Good idea. I've requested a thread name change

 

We'll still post all the features but the title will be a bit more what people are looking for.