Figma Provider for NextAuth NextJS. Tested on latest versions

FigmaProvider.ts

import { Provider } from "next-auth/providers";

const clientId = process.env.FIGMA_CLIENT_ID
const clientSecret = process.env.FIGMA_CLIENT_SECRET
const base64Encoded = Buffer.from(`${clientId}:${clientSecret}`).toString('base64');
const authHeader = `Basic ${base64Encoded}`;

export const FigmaProvider: Provider = {
    id: "figma",
    name: "Figma",
    type: "oauth",
    authorization: {
      url: "https://www.figma.com/oauth",
      params: {
        scope: "files:read",
        response_type: "code",
        state: "YOUR_STATE_TO_UPDATE_TOKENS"
      },
    },
    token: {
      url: "https://api.figma.com/v1/oauth/token",
      async request(context: any) {
        const provider = context.provider;
        const res = await fetch(
          `https://api.figma.com/v1/oauth/token?redirect_uri=${provider.callbackUrl}&code=${context.params.code}&grant_type=authorization_code`,
          { 
            method: "POST",
            headers: {
                'Authorization': authHeader,
                'Content-Type': 'application/x-www-form-urlencoded'
            }
        }
        );
        const json = await res.json();
        return { tokens: json };
      },
    },
    userinfo: "https://api.figma.com/v1/me",
    profile(profile) {
      return {
        id: profile.id,
        name: `${profile.handle}`,
        email: profile.email,
        image: profile.img_url,
      };
    },
    clientId: process.env.FIGMA_CLIENT_ID,
    clientSecret: process.env.FIGMA_CLIENT_SECRET
  };