A Builder product Skill for Claude · ChatGPT

Circuit
AI.

Tell your agent what you want to train. It builds the circuit, picks the demo videos, and hands you back a timer link that runs the whole session out loud.

Open the timer ↗
You say

"Give me a 20 minute glute and core circuit I can do with one kettlebell."

You get

Your agent generates a link which takes you to the circuit. You get voice cues calling out each exercise, the halfway mark, and your three second count down. Youtube demo videos are included to help you through the work and to preview the next move during rest.

What it is

04 parts, one session
01

The skill

A small skill your agent loads on demand. It knows the circuit schema, sensible work and rest times, and how to encode a workout into a link that opens correctly every time.

02

The timer

One self-contained page. Prep countdown, work and rest phases, per-station colour coding, progress bar, pause, skip, and a wake lock so the screen stays on.

03

Coaching

Spoken station names, a halfway call, a three-two-one countdown, tones and haptics on every changeover. You never have to look at the phone mid-set.

04

Totally free

The whole workout lives in the URL, so there is nothing to save and no account to make. The service if totally free, no ads and fast. Ask your agent to remember your circuits and set reminders to manage your workout plan.

Install it

set up once, use from your phone

Mobile apps do not install skills directly. You add the skill once from a desktop browser, and it travels with your account, so from then on you can ask for a workout from the Claude or ChatGPT app on your phone.

01 / claude

Claude

Web, then the mobile app

Add it as a skill on your account.

  1. Download the skill files: SKILL.md and build-link.mjs from mikemiller.uk/circuit/skill, and zip the circuit-timer folder.
  2. On claude.ai, open Settings → Capabilities → Skills and upload the zip.
  3. Open the Claude app on your phone and ask for a workout. Claude loads the skill when the request matches it.

If you would rather not use Settings, create a Project called Workouts and attach the two files to the project knowledge instead. Same result, scoped to that project.

02 / chatgpt

ChatGPT

Project, then the mobile app

Attach it to a project so every chat in there can use it.

  1. On chatgpt.com, create a project called Workouts.
  2. Save mikemiller.uk/circuit/skill.txt and upload it to the project files. It is the whole skill in one plain-text file.
  3. In the project instructions, paste: Follow the attached skill.txt when I ask for a circuit or interval workout. Build the circuit JSON, encode it as URL-safe base64, and give me the link.
  4. Open that project in the ChatGPT app on your phone and ask for a workout.

ChatGPT cannot run the bundled Node script on mobile, so it encodes the link itself. Open the link once before you start to check the stations read correctly.

03 / first run

Ask for
a workout

What to say

Be specific about time, kit and what you want to train.

  1. "Build me a 25 minute full-body circuit with a kettlebell and a mat, two rounds."
  2. "Shorter rests, and swap the burpees for something quieter — I'm on a first floor flat."
  3. "Same again but 12 minutes, core only."

Each reply is a fresh link. Use your agents native memory and reminder features to manage a workout plan.

Built by the Builder crew
Start the
clock.

Circuit AI is one of ours: prototyped in a couple of hours, then productionized the way we do everyone else's. Want us to do the same for you?

Book a call ↗