Hugin

Hugin stitches multi-shot panoramas with real control over the process: automatic control point detection, lens correction, exposure blending, and projection choices that consumer tools hide from you. Results can match commercial stitchers like PTGui when you put in the effort, and the assistant mode handles easy cases in three clicks.

The interface is genuinely dated and the learning curve for manual control points is steep. Development has slowed to maintenance-level releases, so don’t expect modernization — but the math it does hasn’t changed, and it still works. If your camera or phone already stitches well in-device, you may not need it at all.