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GMass vs Substack
GMass: Cold email outreach and mass email inside Gmail. Substack: Writers making money doing the work they believe in. Same fact set for both, straight from each vendor's docs.
GMass
- Free tier
- No free plan; free trial capped at 50 emails/day
- Paid from
- $20/mo (Standard, billed annually; $29.95 monthly) · pricing page
- Public API
- Yes docs
- MCP server
- Community · No official vendor MCP; third-party server via viaSocket
- Best for
- Cold email outreach and mass email inside Gmail
- Website
- https://www.gmass.co
Substack
- Free tier
- Free to publish, no subscriber cap
- Paid from
- No monthly fee; 10% of paid subscription revenue plus Stripe fees · pricing page
- Public API
- Yes docs
- MCP server
- Community · Community servers on GitHub only
- Best for
- Writers making money doing the work they believe in
- Website
- https://substack.com
Which one?
GMass suits cold email outreach and mass email inside gmail. Substack suits writers making money doing the work they believe in. Pricing changes; the fact tables above link both vendors' live pricing pages. For the rest of the field, see GMass alternatives, Substack alternatives, or the full table.