Here are some help desk software available as SaaS. And some highlights that I can catch on each of them.
- groovehq.com – mail-look, neat and easy, only 2 package – free or usd5/agent/mo get all, in slack app, offer API
- desk.com – usd20/mo for unlimited agents
- cayzu.com – starts from usd12/agent/mo
- freshdesk – in slack app,
- zendesk – in slack app
- nethelpdesk – min 10 agents, seems bit on high side
- reamaze.com – usd20/agent/mo
- talkus.io – highly integrated with slack. support via slack, usd48/90/month for unlimited agents
- liveagent – ladesk.com – starts from usd12/agent/mo
- kayako.com – usd20/agent/mo
more
http://www.pcmag.com/article2/0,2817,2489457,00.asp