buffer and metricool are genuinely solid starting points for scheduling, and u/Green-Carpet1832's point about self-hosting SocialScheduler is worth a look if you want free forever. the thing nobody mentions about these tools is they all hit the same wall: scheduling is the easy part, repurposing across platforms is where it breaks.
a linkedin post and an instagram caption for the same idea need different formats, different lengths, different tone. buffer just posts whatever you wrote. you still write four versions manually. if you want actual automation (one piece of content becomes platform-specific versions, queued and scheduled without you touching each one), that's n8n or make.com wiring a claude or gpt call between your source content and each platform's scheduler.
around $10-15/mo total, and the formatting logic lives in a prompt you control. happy to share the architecture if that direction is useful.