Here you go: Online LDAP Test Server
It’s free, contains data, browsable.
Make sure you use LDAP v3 when trying to bind.
Example of using from command line:
ldapsearch -W -h ldap.forumsys.com -D "uid=tesla,dc=example,dc=com" -b "dc=example,dc=com"
Password: password
Returns:
# extended LDIF
#
# LDAPv3
# base <dc=example,dc=com> with scope subtree
# filter: (objectclass=*)
# requesting: ALL
#
...
# search result
search: 2
result: 0 Success
# numResponses: 16
# numEntries: 15