Substack Post Mix

Compare a Substack publication’s own formats to see which ones readers react to and what to publish more or less of.

v0.1.0

View example draft · How to use

Example draft

Lenny’s Newsletter

The latest 20 posts, 11 October to 3 November.

The answer

The weekly "How I AI" roundups get a median of 250 reactions; the podcast episode posts they link to get 12, about a twentieth.

Free and paid

Paid essays come second at 121 and draw almost all the comments. The paid "Community Wisdom" posts get only 17.

What to change

Put each episode’s best takeaways in the roundup and keep the episode post short. Keep the paywall on essays, and fold Community Wisdom into the roundup or make it free.

From a real run on 2026-11-08.

What you get

  • Posts grouped by format with median reactions and restacks
  • Free against paid posts
  • What to publish more of, merge or drop

Good fit

  • Reviewing your own newsletter’s content mix
  • Benchmarking another publication

Not for

  • Open rates or paid conversions, which are private
  • Topic research; use substack-editorial-radar

How to use

An Agent that can read the complete Skill folder. Live research also needs a SandBase connection; supplied material can be used without a lookup. One Substack call costs about $0.044.

Download and unpack the complete Skill folder, keep its references, and use it with a local Agent that supports Skills.

Download Skill v0.1.0

Ask your Agent

Use substack-post-mix on lennysnewsletter.com. Which formats get the most reactions, and what should the newsletter change?

  1. Read the posts

    Pull the publication’s latest 20 posts with reactions and comments.

  2. Group them

    Group by format and recurring series, and by free or paid.

  3. Compare

    Compare median reactions and say what to change.

FAQ

How do I use this Skill?

Download and unpack the whole Skill folder, including references, into your Agent’s supported Skill directory. You can also ask the Agent to read its SKILL.md and follow the instructions. Run it locally with your own material.

What counts as a reaction?

The hearts readers give a post on Substack. Email opens are not public.