Professional
Toon Boom Harmony ($25-115/month) — Industry standard for TV and film animation. Used by studios behind Rick and Morty, Castlevania, Archer. Vector and bitmap tools, bone rigging, node-based compositing.
TVPaint (€500-1,500) — Frame-by-frame bitmap animation preferred by indie filmmakers. Beautiful brush engine, onion skinning, X-sheet.
For more on this topic, see our guide on character animation basics: 12 principles explained.Mid-Range
Clip Studio Paint ($49.99 one-time or $2.49/month) — Originally for manga/comics but excellent animation timeline. Up to 24fps, onion skin, vector and raster.
Free
OpenToonz — Open source, used by Studio Ghibli. Powerful but steep learning curve. Krita — Free painting app with solid animation features. Frame-by-frame, onion skinning, export to video. Pencil2D — Lightweight, beginner-friendly frame-by-frame tool.
Verdict
Start with Krita or Pencil2D (free). Upgrade to Clip Studio Paint for serious work. Go Toon Boom for professional production.