Update your Shopify theme and keep your custom code.

Molt carries your changes into each new Dawn or Horizon release, builds it as a draft, and shows you every page before you publish.

See How It WorksSee Pricing

free to see what's custom · $49 when you publish an upgrade

Molt's review page: 8 changes found, 7 kept as they were, 1 combined with Shopify's new code and 0 needing approval.
  • Dawn 14.0.0 to 16.1.1
  • Horizon 2.0.3 to 4.4.0
  • 446 public Dawn themes merged in testing
  • Every upgrade starts as a draft

When a theme release changes the code you customized, someone has to redo that work by hand, and Molt does it for you.

How an upgrade works

Why Molt?

A crab outgrows its shell, sheds it and keeps everything inside.

Molt is that for your theme. The old release comes off, the new one goes on, and the work you paid for stays.

We do four things

  1. 1

    Read

    Molt compares your theme with the original release and lists every change in plain words. A size guide reads as a size guide, with the files one click away. This part is free.

    A theme's page in Molt: 7 code changes, 1 settings item and 119 lines of code added against Dawn 15.4.1, with what's new in Dawn 16.1.1 and a button to prepare the upgrade.
  2. 2

    Merge

    Edits that sit apart from the release merge line by line. When you and Shopify changed the same lines, a model combines them, explains what it did and flags anything a person should check.

    Three cards from Molt's review page: a removed file marked Needs your OK, a same day dispatch note marked Combined, 90% sure with the model's explanation open, and the changes kept as they were.
  3. 3

    Compare

    Molt opens your home, collection, product, cart, search and contact pages on both themes and names any section the release leaves out. You can keep your current layout for that page with one click.

    A product page side by side on the live theme and on Dawn 16.1.1, with a note naming the two sections the release leaves out.
  4. 4

    Publish

    The upgrade waits beside your live theme as a draft until you click Publish. Your previous theme stays on the store, so one more click puts it back.

    The upgrade ready to review: your live theme is still the one customers see, with Preview, Publish and Remove buttons.
    The upgrade after publishing: this upgrade is your live theme, with a button to roll back to the previous theme.

What one update costs

A developer redoing it by hand

$200 to $600

For a heavily customized theme, each time a release comes out, plus the wait for their schedule.

Molt

$49

Charged when you publish. Preparing the draft and comparing your pages come with it. Upgrading often? One store is $19 a month.

See All Plans

Developer estimate from Fuel Themes, read November 2026. Your developer's quote may differ.

The same line, changed twice

A store added an attribute to a variant input, and Dawn then rewrote that line. Molt keeps both changes and shows you the result. We merged 446 public Dawn themes this way, and no merchant line was missing in the final pass.

How the Merge Works
The original releasevalue="{{ value | escape }}"
Your storevalue="{{ value | escape }}" data-custom-option="{{ value | handleize }}"
The new releasevalue="{{ escaped_value }}"
Your draft themevalue="{{ escaped_value }}" data-custom-option="{{ value | handleize }}"

What people ask before they install

What happens to my live theme during an upgrade?

It stays exactly as it is. Molt builds the upgrade as a new draft theme beside it, and your store changes when you click Publish. The previous theme stays on your store, so one click puts it back.

Which themes can Molt upgrade?

Dawn and Horizon, the free themes Shopify makes. Molt compares your theme with a clean copy of the release it started from, and it holds clean copies of Dawn 14.0.0 to 16.1.1 and Horizon 2.0.3 to 4.4.0. Supported themes.

Shopify already offers theme updates. What does Molt add?

Shopify copies your theme editor changes and any code edits that don't conflict with the update. When they conflict, you copy the code across yourself. Molt combines those conflicting edits, lists what it did in plain words, compares your pages and tells you what the release removes. Why themes fall behind.

What if Molt is unsure about an edit?

The upgrade marks it Needs your OK and explains why. You read the reason, preview the page and decide. A developer can open the technical details on the same card to see the files and the explanation behind the merge. Reading the review page.

Read the Docs

Let your theme molt

Install Molt and it lists every change on your theme against the original release. Upgrading is a choice you make after that.

See How It WorksRead the Docs