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Connecting remote sites and apps

If you are not running your website or app locally but would still like to use Micro for testing and debugging, there are two options:

Option 1
Exposing Micro via a public domain name
Option 2
Locally resolving an existing domain name to Micro
Requires control over the tracking codeYesNo
Accessible from multiple devicesYesNo
Micro receives first-party cookiesNoYes
Micro receives external IP addressesYesNo

Exposing Micro via a public domain name

This method allows you to get a publicly accessible URL for your Micro, which you can point your tracking code to. You can also send this URL to colleagues for them to inspect the results via the UI (since version 2.0.0) or the API.

The easiest way to achieve this is with a tool like ngrok or localtunnel.

Cookies and IP addresses

Either tool will take care of HTTPS and the required certificates. However, the resulting URL will not be under your domain, so you will not be able to set or receive first-party cookies this way.

You will, however, receive external IP addresses (not something like when you or others browse the website or app pointing to Micro. This might be useful for testing certain enrichments.

After running Micro as usual, you just need to expose the port (by default, 9090):

Sign up, download ngrok and follow the instructions to authenticate your client. Then run this command:

ngrok http 9090

You will see the publicly available URL in the output.

Locally resolving an existing domain name to Micro

This method only works on your machine, but it allows you to connect any website or app to your Micro, even if you don’t control the tracking code.

Let’s say you have a website with Snowplow tracking that points to a Collector hosted at

Cookies and IP addresses

With this approach, because Micro is “pretending” to be behind the actual Collector domain (, it will receive first-party cookies set for that domain.

However, you will only get local IP addresses (like in your data, because the traffic never leaves your machine. This might be relevant for testing some enrichments.

If you are using a web browser to test your site or app, you can spoof a specific IP address using a browser plugin that sets an X-Forwarded-For header. For example, here are plugins for Chrome and Firefox. Install the plugin and set the IP address to your liking.

Generate a local SSL/TLS certificate

Chances are that the website in question uses HTTPS. If so, you will need to configure Micro to enable HTTPS. Otherwise, feel free to skip this step.

First, install mkcert. This tool allows you to easily generate SSL/TLS certificates that your machine trusts.

Now, run the following commands in a terminal (make sure to substitute your Collector domain for

# one-time setup
mkcert -install

# generate a certificate
mkcert -pkcs12

You should now have a local file called with the default password changeit.

Match the Collector configuration

To make sure your Micro behaves the same way as the Collector it’s “pretending” to be, copy the relevant parts of your Collector configuration and pass them to Micro.

The two most important settings are the cookie name (you can set it with as shown on the page linked above) and any custom paths (via a configuration file).

Run Micro

You will need to run Micro as usual, with a few changes:

  • Enable HTTPS, if needed
  • Use port 80 instead of 9090
  • If HTTPS is enabled, also use port 443 instead of 9543

If you don’t need HTTPS:

docker run -p 80:9090 snowplow/snowplow-micro:2.0.0

If you need HTTPS (substitute your Collector domain for

docker run -p 80:9090 -p 443:9543 \
--mount type=bind,source=$(pwd)/,destination=/config/ssl-certificate.p12 \

Modify the hosts file

To conclude the setup, you will have to modify your hosts file (/etc/hosts on Linux/macOS, C:\Windows\System32\drivers\etc\hosts on Windows) to point — the Collector domain — to your local machine. Add these lines:

With this change, whenever your system tries to send data to, it will send it to your Micro instead. Done!


Don’t forget to revert the hosts file change once no longer necessary.

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