FillColor is a free, browser-based flood fill tool built for teachers, students and anyone who needs to colour diagrams, maps or PDF files instantly — no software, no signup required.
FillColor is a free online colour fill tool that works entirely in your browser. Upload any image or PDF — a geography map, a science diagram, a floor plan, a drawing — pick a colour, and tap or click any bounded area to fill it instantly.
It uses a flood fill algorithm — the same technology as the paint bucket in MS Paint — to detect boundary lines and fill only the enclosed area without spilling outside.
Fill multiple regions with different colours, undo and redo actions, adjust opacity, control tolerance for imperfect boundaries, and download as PNG or PDF.
FillColor was built keeping Indian school teachers and students in mind. Geography is a core subject in CBSE and RBSE curricula from Class 6 to 12, and colouring maps is a regular classroom activity.
Most existing tools online require subscriptions or only work with pre-built maps. FillColor works with any image or PDF you already have — your NCERT textbook map, school worksheet, or any diagram from your study material.
It works smoothly on low-end Android phones as well as desktop computers — because most Indian students use mobile devices.