[jtap]

Not sure if this is what you are looking for but https://getsentry.com/welcome/ is open source.

[cyber]

Might as well disclose that Sentry is commercial-ware with a limited free tier:

What happens when my free trial expires?

When your trial expires we'll downgrade you to our free tier. Our free tier is limited to a single user and 250 events per day.

[techdragon]

And also open source. I've run my own sentry installation several times instead of paying for the SaaS one.