# Build a comparison board across websites

Build a browser extension for gathering candidates from different websites and comparing them using the person's own criteria. Build it extremely well for a decision they actually want to make. Follow the [shared launch](../shared/launch.md) and install it in their usual browser.

Choose a real comparison: apartments, equipment, courses, places to stay, or another decision the person is researching. Find out what they care about and which details are difficult to keep track of across open tabs.

## Start with the person's decision

Give each board criteria that fit its purpose. Someone choosing an apartment may care about the commute, natural light, and whether their piano will fit. Some details come from the listing; others come from a visit or the person's own judgment. Make room for both.

Let the person add, rename, and refine criteria as their thinking develops. Keep factual details, personal observations, and unanswered questions understandable. A missing detail should remain something to find out.

Provide an initial board that is immediately useful for the chosen decision. The person should be able to see candidates together, inspect their differences, and open an individual candidate for more detail.

## Collect from the page

Let the person save a candidate from the current website, capturing useful details, an image where appropriate, and the source address. Show the captured information so they can correct it and add what matters to them. Make capture work well on the sites they are using for this decision.

Preserve the meaning of amounts and measurements. A price needs its currency and the terms that make it comparable; a room measurement needs its unit. Keep the source wording available when a detail needs interpretation. Let the person recognize whether two listings refer to the same candidate and combine them deliberately when appropriate.

Keep track of when information was collected. Prices, availability, and descriptions can change. The person should be able to return to the source and update a candidate while retaining notes they made themselves.

## Help them compare

Give the board enough space and clarity to work with several candidates. Let the person narrow a shortlist, order or group entries in useful ways, and see the criteria important to them. Long notes and useful photographs should remain accessible from the comparison.

Help the person see tradeoffs. A cheaper apartment may have a worse journey to work; a more expensive course may meet at a time they can actually attend. If they want weighted scores, make the weighting and its effect understandable. Their observations and unresolved questions should remain available alongside any score.

Let them save a decision and its reasons while retaining the candidates they considered. Export a readable board or summary they can discuss with someone else. Preserve source links and personal notes in that result.

## Use it for a decision

Explain the extension's page access, saved information, and update process. Keep boards persistent and give them an export and recovery path under the shared launch's ownership guidance.

Deliver the working extension and gather several real candidates. Add a criterion the websites did not supply, correct a captured detail, and compare the shortlist. Judge whether the person can understand the options more easily than by switching between their original tabs.

Explain how information from several sources can be organized around the person's question. Later projects can share a board with a partner or connect it to a research library, preserving the sources, observations, and decision already recorded here.