How it works
Two tools. One job: don't waste a send.
The Pre-Flight Inspector
You paste your newsletter's HTML — the exact export from your ESP — and it runs three checks that catch the mistakes you can't see in your ESP's own preview.
Gmail clipping
Gmail clips any message once its rendered HTML crosses 102,400 bytes — cutting off everything after that point, including your unsubscribe link. We measure your exact byte size and tell you if you're over, not just close.
Spam trigger scoring
We scan your copy against a weighted list of phrases that hurt inbox placement — things like "100% free" or "act now" — and show you exactly which ones triggered, not just a vague score.
Mobile truncation
Most phone inboxes cut off around 40 characters for both subject and preview text. We show you what actually renders before the cutoff, so you know if your hook survives.
The Verified Swap Exchange
Cross-promotion only works when both sides bring roughly the same audience. We do the verification and the matching so you're not guessing whether a swap is fair.
- 1
Connect your ESP, read-only
beehiiv, Kit, or Substack. We never get write access — just enough to read your subscriber count and open rate.
- 2
We calculate your effective reach
Subscribers × open rate. A newsletter with 20,000 subscribers and a 15% open rate has less real reach than one with 5,000 subscribers and a 60% open rate — we match on the number that actually matters.
- 3
Get matched, same niche, within 20%
We surface up to 3 newsletters in your niche whose effective reach is within 20% of yours, ranked by how close a match they are.
- 4
Request a swap
One click sends a request with a generated tracking link, so you can both see what the swap actually drove.