GIMP

A swiss knife for image manipulation.

PhotoFlow

A non-destructive photo retouching program including RAW image development.

ImageMagick

A suite of command-line utilities for modifying and working with images.

GraphicsMagick

GraphicsMagick is usually faster than ImageMagick.

CHDK

Canon Hack Development Kit, for Canon cameras.

Magic Lantern

A software enhancement that offers increased functionality to Canon DSLR cameras.

Autoexec Hack

Compilation of hacks for GoPro Cameras.

PTool Firmware Manipulation Tool

Change the video recording parameters of Panasonic's cameras.

Nikon Hacker

Nikon Patch and Nikon Emulator, 2 softwares for Nikon cameras.

Xiaomi Yi Autoexec

Compilation of autoexec scripts and mods for Xiaomi Yi camera.

LibGphoto2

C APi for Digital camera access and remote control. Java,python,C#, and much more bindings.

OfxCanon

OpenFrameworks addon for the Canon EDSK.

Edsdk4j

Canon SDK for Java.

GoPro

API for controlling GoPro Hero 3 Camera from Node.js.

GoPro

GoPro Hero 4 - Python API.

GoPro

A Python library and a CLI that can interface with GoPro HERO3, HERO3+, and HERO4 cameras over http.

GoPro.Hero

A lightweight c# library to access and control GoPro HERO.

SonyPy

Python module for Sony Camera Remote API.

Timelapse-sony

Android app for creating timelapse via "Ctrl with Smartphone" mode or connected by NFC.

Remoteyourcam-usb

Control your Canon or Nikon DSLR camera from your Android device through USB.

digiCamControl

DSLR camera remote control open source software.

Digitaltruth

Film development chart.

Darktable

An open source photography workflow application and RAW developer.

RawTherapee

A cross-platform raw image processing program.

Photivo

A multi platform photo processor for RAW and bitmap images with 16 bit precision.

Raw Studio

Read and manipulate RAW images from digital cameras.

UFRaw

A utility to read and manipulate raw images from digital cameras.

DCRaw

Decoding raw digital photos in Linux.

Lightzone

Open-source digital darkroom software for Windows/Mac/Linux.

Fotoxx

A Linux program for editing photos and other images.

Luminance

A complete workflow for HDR imaging.

QPSFTMO

HDR Tone Mapping GUI for Linux.

PFS Tools

A set of command line programs for reading, writing and manipulating HDR images and video frames.

Hugin

An easy to use cross-platform panoramic imaging toolchain.

Panorama Tools

A framework for re-projecting and blending multiple source images into immersive panoramics of many types.

Shotwell

A photo manager for GNOME 3.

DigiKam/ShowFoto

Open Source Photo manager for KDE/Gnome desktop.

GPhoto

A program and library framework that lets users download pictures from their digital cameras.

Lychee

A great looking and easy-to-use photo-management-system you can run on your server, to manage and share photos.

Simple Gallery

A Android gallery app for viewing photos and videos similar to android stock gallery with support for file copy/move/rename/delete/share.

Leaf Pic

Material-designed android gallery alternative.

A Photo Manager

Manage local photos on Android: gallery, geotag with photomap, tags, find, sort, view, copy, delete, send,...

PhotoPrism

PhotoPrism™ is a server-based application for browsing, organizing and sharing your personal photo collection.

ExifTool

A program for reading, writing, and manipulating image, audio, and video metadata.

Exiv2

Exiv2 is a C++ library and a command-line utility to read, write, delete and modify Exif, IPTC, XMP and ICC image metadata.

Rapid Photo Downloader

A photo and video downloader for the Linux Desktop.

Entangle

Entangle provides a GUI for taking photographs with a digital camera completely controlled from the computer.

Hughski

DisplayCal

Open source display calibration and characterization.

Open360viewer

Open source 360° media viewer.

Geeqie

An image viewer and image organiser program for Unix-like operating systems.

FEH

An X11 image viewer.

GIMP Plugin Registry

Cinepaint

A program for painting and retouching bitmap frames of films based on GIMP.

Flickr Open Source Photography Group

/r/FOSSPhotography

Community about Free open source software for Photography on reddit.

Open Source Photography Community on Google+

. Open-source photography community on Google+.

Open Source Photography Group on Facebook

Open Source Photography Sub on Reddit

Open Source Photography Group on 500px

PIXLS.US

Community dedicated to tutorials, workflows, and showcases of high-quality photography using Free Software tools

Unsplash.com

Free (do whatever you want) high-resolution photos, licensed under the Unsplash License (changed from CC0)

Pexels.com

Royalty free high-resolution stock photos, licensed under Creative Commons Zero (CC0)

Pixabay.com

Royalty free stock photos and videos, licensed under Creative Commons Zero (CC0).

Shutterography.com

Free Photos.

FFmpeg

A complete, cross-platform solution to record, convert and stream audio and video.

Virtualdub

A free video tool for basic editing and encoding.

Natron

A node-based compositor based on the same principles as state-of-the art tools used in film and television post-production.

ButtleOFX

A simple, user-friendly and open source compositing software.

Blender

This open source 3D graphics has tools for video editing.

Shotcut

A free, open source, cross-platform video editor.

OpenFX

An Open Plug-in API for 2D Visual Effects.

TuttleOFX

An image processing framework based on OpenFX plugin format.

Vid.stab

A video stabilization library which can be plugged-in with Ffmpeg and Transcode.

Frei0r

A large collection of free and portable video plugins.