| Owner | Meta | Elon Musk - X is part of xAI, now owned by SpaceX | Bluesky Social PBC |
| Audience size | 500M+ monthly users | 600M monthly (2024 claim), now behind Threads on mobile daily use | 46M+ registered accounts |
| Post length | 500 characters, plus long text attachments | 280 free · up to 25,000 with Premium | 300 characters |
| Video | Up to 5 minutes | Longer videos with Premium | Up to 3 minutes |
| Main feed | For you (algorithmic) + Following | For You (algorithmic) + Following | Following + any custom feed you pick |
| Discovery | Topic tags (1 per post), communities, search | Hashtags, trends, search, Communities | Custom feeds, starter packs, search |
| Ads | Yes - global since Jan 2026 | Yes | No ads |
| Native scheduling | Yes - up to 75 days ahead | Via X Pro (Premium) | No - third-party tools |
| Direct messages | Yes (since 2025) | Yes | Yes |
| Developer API | Free official API | Paid tiers | Free, open protocol |
| Openness | Connects to the fediverse (ActivityPub) | Closed platform | Open AT Protocol, custom domain handles |
| Built-in AI | Meta AI across Meta apps | Grok | None built in |
| Account needed | Instagram account or Threads-only profile | X account | Bluesky account |