CMass vs GMass
Both work inside Gmail. Both do mail merge from Google Sheets. Here's where they diverge — and how to decide which is right for your outreach.
TL;DR
If you want AI-personalized emails that actually sound human — at scale, without a Claude account — CMass wins on that dimension. GMass is a solid, established tool with a larger community but no native AI personalization.
Feature comparison
Pricing
Where CMass pulls ahead
AI personalization at scale
Claude reads every row of your contact data and writes a unique, natural-sounding message for each recipient. GMass has no equivalent — you're limited to merge tag substitution.
No separate AI account
CMass runs Claude on our infrastructure. You pay one flat fee and get unlimited AI personalization. No Anthropic account, no API key, no per-token charges.
Built for Manifest V3
Chrome's new extension standard. CMass was built on MV3 from day one — which means better performance, better security, and no risk of being removed from the Web Store as Chrome phases out MV2.
Common questions
Does CMass work the same way as GMass — directly in Gmail?
Yes. CMass is a Chrome Extension that adds a panel directly inside Gmail. There's no separate web app to log into — your campaigns live next to your inbox.
What makes CMass's AI personalization different from just using merge tags?
Merge tags do find-and-replace with your data. CMass's AI (powered by Claude) reads all your contact data — name, company, role, any custom field — and generates a unique, natural-sounding opening line or paragraph for each recipient. It's the difference between 'Hi {{first_name}}' and an email that sounds like you actually researched the person.
Do I need a Claude or Anthropic account for CMass's AI features?
No. CMass runs Claude on our infrastructure. You get AI personalization as part of your CMass Pro subscription — no extra accounts, no API key, no per-token charges on your end.
Can I import my GMass campaigns into CMass?
If your contacts are in Google Sheets or a CSV (which GMass users typically use), you can import them into CMass in minutes. Template content can be copy-pasted into the CMass template editor.
Is GMass ever the better choice?
GMass has been around longer and has a large user base. If AI personalization isn't important to you and you're already comfortable with GMass, switching has a learning curve. CMass is particularly compelling for sales teams doing personalized outreach at volume, where the AI personalization can meaningfully lift reply rates.
Ready to try the AI-powered option?
Free plan, no credit card. 50 emails/day to see if CMass works for your outreach before you commit.
Add CMass to Chrome — Free