ByteByteGo
Alex Xu
Beat the incumbent agency head-to-head while spending ~5.6× less.
Alex Xu's system-design newsletter for engineers, 1M+ technical readers. Launched under hard brand constraints, went head-to-head with the incumbent agency, and won. They had a head start. It didn't help.
The brief
ByteByteGo is Alex Xu's system-design newsletter for software engineers, a developer-education brand with 1M+ technical readers. I launched paid acquisition under hard brand constraints (no name, no face) and went head-to-head with the incumbent agency.
What I did
- Launched with brand guardrails (no name/face), uploaded buyer lists for lookalikes, navigated a US+CAN vs ROW split.
- Ran concept + copy across Confession, Stop X/Start Y, X-but-for-Y, UGC-podcast and cheat-sheet lead-magnet angles.
- Restructured into BROAD + LEADS, cutting blended CPL ~27% and halving US+CAN CPL.
- Co-introduced cost-per-engaged-sub (CPES) and proved we beat the incumbent on the metric that maps to product value.
The numbers
Managed ad spend is windowed to my time on the account, not the lifetime account total.
How the winning ad got made
Everyone says they have a process. Here's mine actually running, on the ad that helped take this account from the incumbent agency.
- 01
Steal the audience's words
Before a single dollar moves, I mine Reddit, Quora and the client's own readers for the exact language they use. For ByteByteGo: how engineers really talk about system design, interviews and keeping up. That becomes the message bank every line is pulled from.
- 02
Write like the brand, sell like direct response
One concept, five variations: same headline and CTA, a different promise each, all in the brand's voice. The selling instinct comes from my own direct-response years, when my copy either converted or I didn't get paid.
- 03
Buy against CAC, not vibes
Launched into a BROAD + LEADS structure and judged on cost per engaged subscriber, not clicks. Scaled the winner, killed the rest. Blended CPL fell from $4.42 to $1.41 while spending 5.6× less than the agency we replaced.
- 04
Turn the win into a machine
Then the whole flow became a Claude Code skill: it researches, writes the variations, builds the Canva design and the designer brief. The next winner takes hours instead of days. I automate my own job so I can do more of it.
CPL $4.42 → $1.41 The ads
