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Tags is metadata stored along with a transaction, similar to headers in an HTTP request.


There are lots of use cases, but here are a couple:


If you want to set a content type for your data (e.g. image/png, text/html etc). This will affect how your data will be rendered in the browser.


You can label transactions with your app name, so you can filter transactions by application.

How to add tags to a transaction

They're defined by name/value pairs.

const nft = fs.readFileSync("/path/to/nft.png");

const tags = [{name: "Content-Type", value: "image/png"}];

const transaction = bundlr.createTransaction(nft, { tags });