When you build a redesign on a copy of your theme, edits made to the live theme in the meantime are lost on publish. ThemeMerge compares both themes against a baseline you record when the copy is made, so it knows what each side changed. Theme editor JSON merges key by key, keeping sections added on either side. Liquid, CSS and JavaScript merge line by line. You decide the remaining conflicts, then download the merged theme to upload and preview. Your live theme is never modified.

• Three-way compare of live theme and working copy against a recorded baseline
• Theme editor JSON merged key by key, so sections added on both sides are kept
• Section and block order merged so both sides' additions stay in place
• Resolve conflicts one at a time, per file, or by editing the result directly
• Reads your live theme only and never writes to it