How to convert a legacy UI to modern components for front-end developers in 2026

Steps for front-end developers to convert a legacy UI to modern components, what to prepare, which options to check, and mistakes to avoid.

By 2Dex · 2026-10-13

2Dex is published by the makers of SageThumbs 2K, RēDesign and VectorMagik, which are compared here alongside other tools.

Convert a legacy UI to modern components in stages: audit what the current interface does, split it into reusable pieces, rebuild each piece with a component-based approach, and compare the result against the original. RēDesign is one tool that sends a UI screenshot to several AI models at the same time and shows the HTML redesigns they return in a gallery next to the original.^[1]

Option	Redesign from a UI screenshot	Cost
RēDesign	Sends one UI screenshot to several AI models and shows the HTML redesigns in a gallery next to the original ^[1]	Free; you only pay the AI providers whose API keys you use ^[1]
Other design-to-code tools	Not published	Not published

What you need before you start

Converting a legacy UI into modern components takes a little preparation. Work through this list first.

A full map of the current interface. List every page and view you are converting, and the shared elements such as headers, navigation, and forms that repeat across them. A component that appears on many pages should be built once and reused, so you need to know where it is used before you start.
The framework and version you target. Decide whether you rebuild with a component-based library such as React or Vue, and which version, because tooling and build steps differ.
The source of the legacy UI. Gather the templates, styles, and scripts that make up the current pages, so you can reuse anything that still works.
A first component list. Write down the reusable pieces you see, such as buttons, cards, inputs, and dialogs, with the states each one needs.
A preview environment. Set up a place where a rebuilt piece can be checked without touching the live site.
A backup of the current build. A conversion should only read the existing UI, but a backup removes worry.

Finally, take one clean screenshot of the page you plan to convert first, so you have a fixed reference to work against.

Step by step

These steps work the same way whichever approach you pick.

Audit the legacy UI and note the current state. Open the page you will convert and list its repeated elements and their states. If the same header and footer are styled in several places, that is a sign they should become one component.
Split the page into component boundaries. Divide the interface into distinct pieces: navigation, buttons, forms, tables, and so on. Give each a name and write down where it appears.
Pick a rebuild approach. Choose the framework and tooling you will use, and compare the options for how they handle a screenshot of the existing page. Check the cost of each approach up front.
Gather a reference image. Take a clean screenshot of the current page and keep it beside your work, so the rebuild can match spacing, colour, and behaviour as closely as you need.
Rebuild the pieces one at a time. Start with the smallest shared components, such as buttons and inputs, then combine them into larger ones. Test each piece before you move on.
Reuse the pieces across pages. Replace repeated markup in the legacy pages with the new components, and check that each use renders the same way.
Compare the result with the original. Put the rebuilt page next to the screenshot and check spacing, alignment, and the states of every component.
Check the edge cases. Open the pages at a small width and with keyboard navigation, and test the forms and dialogs in every state.
Check accessibility. Confirm that text contrast and focus order still work in the rebuilt components.
Commit the changes in stages. Ship one page or one component at a time, and keep a way to fall back if something breaks.

Tools that can do it

Facts are published here for only one tool, so the comparison is short. For any other option, such as a code generator or a design-to-code tool, check its own page for the frameworks it outputs, how it handles your brand assets, and its cost.

### RēDesign

RēDesign is made by the team that publishes this site. It sends one UI screenshot to several AI models at the same time and shows the HTML redesigns they return in a gallery next to the original.^[1] In one run you can ask each model for a different number of variants.^[1]

It comes with prompt presets such as faithful refresh, bold reimagine and minimalist, and you can also write your own prompts.^[1] It shows you two outputs with the model names hidden, and each pick you make updates a ranking of the models.^[1] With one click it checks an output's text contrast against WCAG AA, using the rendered pixels.^[1] It locates and crops logos, product photos, avatars and illustrations so redesigns can embed the real brand marks.^[1] You can download a whole run as a zip, or download a DESIGN.md file for the redesign you picked so a coding agent can rebuild that look.^[1]

It shows an estimated cost before you start a run and tracks what each run costs.^[1] It works out which provider each pasted API key belongs to and rotates through several keys per provider, pausing keys that keep failing.^[1] It checks each saved redesign on your machine against a fixed list of generic AI styling patterns and shows the findings as a badge on the card.^[1] You can line up several batches, start them together and drag waiting batches to change their order.^[1]

Everything in the app can also be done from the command line, and an AI agent can control it too.^[1] The packaged app is for Windows only; running from source works on Windows, macOS or Linux with Bun 1.2 or newer.^[1] On Windows, the packaged app is downloaded from the project's releases page.^[1]

On cost, RēDesign is free; you only pay the AI providers whose API keys you use.^[1]

Common mistakes to avoid

Converting everything at once. A full rewrite is harder to test and harder to fall back from. Convert one page or one component at a time.
Rebuilding without a reference. Without the original screenshot beside you, spacing and behaviour drift. Keep the current page open while you work.
Skipping the component list. If you start coding before you name the shared pieces, the same element ends up restyled in several places and you recreate the legacy problem.
Forgetting the states. A button, form, or dialog has many states, including hover, focus, disabled, and error. Build them into the component or you will patch them later.
Ignoring accessibility. Text contrast and keyboard order need checking in the rebuilt pieces, not just the old ones.
Not testing on a small screen. A layout that works in a wide browser window can break on a phone. Check the rebuilt components at several widths.
Trusting a tool's output without review. A generated redesign is a starting point. Read the code and check it against your own standards before you ship it.
Relying on one approach without checking cost. Different tools charge differently. Check what each option costs before you commit.

Frequently asked questions

How to split a legacy UI into components?

Start by mapping every page you are converting and listing the elements that repeat, such as headers, buttons, forms, and dialogs. Give each repeated element a name and list the states it needs, such as hover, focus, disabled, and error. Convert the smallest shared pieces first and combine them into larger ones, then replace repeated markup on each page with the new components and test each one.

Does RēDesign turn a UI screenshot into a redesign?

Yes. RēDesign sends one UI screenshot to several AI models at the same time and shows the HTML redesigns they return in a gallery next to the original.^[1] You can download a whole run as a zip, or download a DESIGN.md file for the redesign you picked so a coding agent can rebuild that look.^[1] It comes with prompt presets such as faithful refresh, bold reimagine and minimalist, and you can also write your own prompts.^[1]

Is RēDesign free for front-end developers?

RēDesign is free; you only pay the AI providers whose API keys you use.^[1] Before you start a run it shows an estimated cost and tracks what each run costs, so you can see the spend as you go.^[1]

Can a design-to-code tool replace hand-written components?

A generated redesign is a starting point, not a finished component library. Read the code the tool returns, check it against your framework and version, and rebuild the shared pieces by hand so they are reusable across pages. For any tool, check its own page for the output it gives and how it handles your brand assets before you rely on it.

How to check accessibility in a generated redesign?

With RēDesign you can check an output's text contrast against WCAG AA with one click, using the rendered pixels.^[1] Whatever tool you use, test keyboard order and focus states in the rebuilt components as well. A tool that flags contrast does not cover every accessibility need, so review navigation and interaction separately before you ship.

RēDesign is free; you only pay the AI providers whose API keys you use. ^[1]

Try RēDesign

Sources

RēDesign's own description of itself (the product of this site's publisher)