Have you seen testserver.host?
As part of building HTTP Toolkit I often need a remote servers for testing edge cases, so I've built one! Now fairly mature & stable. It's httpbin.org plus badssl.com plus lots of extras.
testserver.host
Extras you say?
* More endpoints, like /echo (echoes back raw HTTP), /encoding/zstd, and /error/reset
* Websocket support
* Faster & more reliable than either
* Combining HTTP & TLS tests (give me an expired cert, then a 404 response)
* Chainable endpoints, for both HTTP & TLS
Faster & more reliable?
1. Horizontal autoscaling & globally distributed: low latency everywhere, failover, easy to scale.
2. Cert issuance 100% automated, with ACME and a local CA (many badssl cases need manual setup, and so rot: failing due to expiry, not the real cause).