Adobe After Effects!

Natron is an open source, cross platform nodal compositing application. It is built around industry standard open source tech such as OpenFX, OpenEXR, OpenColorIO and OpenImageIO. The feature set includes realtime playback/RAM cache, multi-threaded rendering, 2d tracking, rotoscoping, grading, animation via f-curves and 3rd party OpenFX plugin support. All contained within a familiar, intuitive interface with an XML based project file format.

HitFilm merges FXHome VisionLab Studio , FXHome Effectslab and FXHome CompositeLab into one software.

Blackmagic Fusion (formerly known as Fusion and eyeon Fusion) is an image compositing software program created by eyeon Software Inc, now developed by Blackmagic Design. It is typically used to create visual effects and digital compositing for movies, TV-series and commercials. It employs a node-based interface in which complex processes are built up by connecting a flowchart or schematic of many nodes, each of which represents a simpler process, such as a blur or color correction. This type of compositing interface allows great flexibility, including the ability to modify the parameters of an earlier image processing step "in context" (while viewing the final composite). Upon its acquisition by Blackmagic Design, Fusion was released in two versions: the freeware Fusion, and the commercially sold Fusion Studio. »

Motion is a compositing application used to create and edit motion graphics, titling for video and film production, and 2D and 3D compositing for visual effects.

ButtleOFX is a simple, user-friendly and open source compositing software. It is based on TuttleOFX,  an open source, modular and sustainable image processing architecture.

Liconcomp allows live content compositing to display screens for digital signage, scoreboards, LED installations, ....

Snowmix is a video mixer tool for mixing live and recorded video and audio feeds. It supports clipping, scaling and transparent overlay of video, png graphics and text. It supports animation of video, images and texts through native commands changing scale, placement, transparency and rotation. Animation and actions can also be controlled through native scripting and an embedded Tcl interpreter. Snowmix is designed for control over low bandwidth links and can work as a standalone CLI based program. Control over both CLI and a TCP connections.Live and recorded video feeds can be fed to the mixer via GStreamer pipelines. Output can be accessed through GStreamer pipelines.OS X on Intel and Linux on amd64/i386/i686/ARMv7 supported. Ubuntu/Fedora/Mint/Debian/OpenSUSE/Chakra and Linero is supported. »

BluffTitler is a Windows desktop app for creating, rendering and playing 3D video effects.

Export the particle effects as static animations onto sprite sheets, animation strips or image sequences in PNG format, or if you develop for the iPhone or iPad, you can export using the PVRTC format (Mac only). If you program games using the powerful Blitzmax programming language, you can also use the effects directly using the TimelineFX Module.

particleIllusion 3.0: award-winning standalone particle effects application that enables you to quickly and easily add a huge variety of particle effects to your images, animation, or video.

PixelConduit Complete is an add-on pack of PixelConduit(free) that provides even more functionality for advanced tasks. If you need to automate live video or post-production workflows, record video streams to disk, or create complex live shows, then PixelConduit Complete is the solution.