Grow your newsletter
by swapping readers
Byline Swap pairs AI-tools Substack writers with complementary newsletters, automates reader list exchanges, and measures exactly which swaps drive free → paid upgrades.
Everything to run a smarter growth loop
Automated Reader Swaps
Set your newsletter niche, audience size, and engagement thresholds. Our matching engine pairs you with complementary AI-tools writers and coordinates swaps — no back-and-forth DMs.
Open Rate Tracking
See exactly how many of your swap partner's readers opened your recommended issue. Track click-through by day, device, and reader segment in one live dashboard.
Paid Conversion Measurement
Know which cross-promotions actually moved free readers to paid. Attribution is linked to Substack upgrade events — so you measure revenue, not just opens.
Three steps, then it runs itself
Connect your Substack
OAuth link syncs your subscriber count, open rate, and niche tags in under 60 seconds.
Get matched automatically
The algorithm surfaces newsletters with overlapping audience interests but non-competing content focus.
Swap and measure
Recommend each other's best issue. Track open rates and paid upgrades from day one.
Your next 500 subscribers
are already reading someone else.
Get full access to the reader list swap network and A/B testing dashboard. $19/month, cancel any time.
No spam. No sharing your list. Cancel any time.