Bun provides a built-in API for working with cookies in HTTP requests and responses. The BunRequest object includes a cookies property that provides a CookieMap for easily accessing and manipulating cookies. When using routes, Bun.serve() automatically tracks request.cookies.set and applies them to the response.

Reading cookies

Read cookies from incoming requests using the cookies property on the BunRequest object:

Bun.serve({
  routes: {
    "/profile": req => {
      // Access cookies from the request
      const userId = req.cookies.get("user_id");
      const theme = req.cookies.get("theme") || "light";

      return Response.json({
        userId,
        theme,
        message: "Profile page",
      });
    },
  },
});

Setting cookies

To set cookies, use the set method on the CookieMap from the BunRequest object.

Bun.serve({
  routes: {
    "/login": req => {
      const cookies = req.cookies;

      // Set a cookie with various options
      cookies.set("user_id", "12345", {
        maxAge: 60 * 60 * 24 * 7, // 1 week
        httpOnly: true,
        secure: true,
        path: "/",
      });

      // Add a theme preference cookie
      cookies.set("theme", "dark");

      // Modified cookies from the request are automatically applied to the response
      return new Response("Login successful");
    },
  },
});

Bun.serve() automatically tracks modified cookies from the request and applies them to the response.

Deleting cookies

To delete a cookie, use the delete method on the request.cookies (CookieMap) object:

Bun.serve({
  routes: {
    "/logout": req => {
      // Delete the user_id cookie
      req.cookies.delete("user_id", {
        path: "/",
      });

      return new Response("Logged out successfully");
    },
  },
});

Deleted cookies become a Set-Cookie header on the response with the maxAge set to 0 and an empty value.