If you are a student or on a tight budget, consider Adobe’s (free mobile/web app) or the 7-day free trial of the current Photoshop. For ongoing free use, open-source editors are the safest choice.
It is important to note that Adobe no longer provides official, free downloads of older Photoshop versions (like CS2, CS3, CS4, etc.) except for a specific, time-limited trial of the current version. Any website offering "free old version" downloads outside of Adobe’s official channels is highly likely to contain malware, spyware, or copyright-infringing cracks. adobe photoshop old version free download