I'm a fan of SQL Developer, have been for years. I especially like User Defined Reports.
Time for some shameless self promotion!

• Here is a presentation I gave to East Coast OUG on 2014 - SQL Developer Reporting. It covers general SQL Developer reporting features and a deep dive into User Defined Reports.
  

Certificates can be a pain.

So if you're trying to use UTL_HTTP or APEX_WEB_SERVICE to reach https destinations you'll be on the hook for obtaining certificates for the target server.

I had access to all the certificates separately and loaded them into a nice fresh new wallet. Unfortunately I couldn't get this to work. I'm working an SR with Oracle now but there doesn't seem to be much expertise on troubleshooting issues, even with

General form

#!/bin/bash
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi

export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=/u01/app/oracle/product/19.0.0.0/dbhome_1
export ORACLE_SID=orclcdb1
export PATH=$ORACLE_HOME/bin:$PATH

while [ true ]
do
  sqlplus -s / as sysdba  >> output.txt << EOF
SELECT * FROM DUAL;
EXIT
EOF
  sleep 10
done

Session Serialization Example

A script to check the query execution time as well as the time to retrieve all records via a FOR cur IN construct:

I run a few websites from a VM on my Synology NAS. The VM has the typical LAMP setup for running Wordpress and Drupal sites. As it is not exposed directly to the internet, Apache serves up all sites on port 80 and I configured the Synology "Application Portal" to forward both port 80/443 requests to it. Application Portal (nginx behind the curtain) also provides handling of SSL Certs on port 443.
So I created 2 Synology Application Portal entries - one to for serving up incoming 80 to ApacheHost:80, and one for serving up incoming 443 to ApacheHost:80.

I opened an SR recently while I was trying to get a feature to work in 19c... was politely directed to this resource... A listing of Oracle features and what version they're available in...
Not sure when this was made available but I hope they keep it up - I much prefer this to trying to find this info in My Oracle Support docs.
Apex App - Features and Licensing Lookup

There are some impressive new features in 20.2. unfortunately my latest upgrades are not going so well.

I see we've got a bundle patch already! Patch 32006852: PSE BUNDLE FOR APEX 20.2 (PSES ON TOP OF 20.2.0.00.20)... But I don't see any of the issues I encountered being addressed.

From most to least severe:

1) ORDS 19.1 munged 3 times over 3 installs

As we move on to 12.2 and 19c we're seeing more instances where simple schema export/import migrations are missing objects on the target database.

If you do object counts after a simple schema migration... Or see something like this pop up in your impdp logs: