Netlify dev doesn't recognize serverless functions in typescript files

I have a React app up and running locally with some working Netlify functions. The Netlify functions are written in Javascript but I would like to convert them to Typescript since that’s what I’m already using for the rest of the app.

However, when I update the file and then rename it from my-function.js to my-function.ts, netlify dev is no longer able to find the function. For example, it doesn’t show up in the list when I run netlify functions:invoke

Since I already use typescript for the rest of the application, is there additional set up needed to use typescript in my Netlify functions?

By the way, this is my netlify.toml file

  functions = "serverless/functions/"
  command = "yarn build"

  from = "api/*"
  to = "/.netlify/functions/:splat"
  status = 200


Hi, @c.ryberg. Netlify Functions only support javascript and Go as languages at this time.

Are you converting the typescript to javascript before deploying?

Hey there, I’m in the process of learning this also. Check out this tutorial where he introduces netlify-lambda in Part 3. It’s a great tutorial all around by the way!

What it will do is take your TypeScript, ES6, etc files and compile them into lambda-compatible code and create a .netlify/functions folder.

For TypeScript, you’ll need a .babelrc file in the folder where your TypeScript functions are located.

Mine looks like this:

  "presets": [
        "targets": {
          "node": "12"
  "plugins": [
  "ignore": ["node_modules"]

Works fine for me using netlify dev so far but still having trouble with netlify deploy at the moment. Hope that helps.

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