What are the main differences between Desk.com (formerly Assistly), Zendesk, Casengo and/or Tender? Which one is the best?

Thanks for the invite Miss Dana...

Well i have nvr been through any of these... i hav no experience in working so i can't judge which one is the best... but according to my knowledge in Media and my thinking, my opinion... there might be something best which each of these sites give us so it depends on the product or the bussiness u deal in and need to go for the one which is suitable rather than choosing the best...

Let me begin with the most important piece of advice I can give you: Don't buy a subscription to ANYTHING until you've taken the time to configure and pilot each of your top two or three choices with a small group of eventual end users (i.e. agents) within your company.  These products, and the 10 to 15 similar offerings in this space, have very different ways of implementing Ticketing, Help Desk, and Knowledgebase systems.  The opinions of people like me can be a good way to gather information and sharpen your expectations.  However, you must invest the time to confirm which product works best for your team, and your environment.  Once you commit to a platform and fully migrate your users and processes, changing vendors will be extremely painful.With that out of the way, here's what I can tell you about Zendesk vs. Assistly.My Experience With Zendesk and AssistlyIn February of 2011, I implemented Zendesk for the IT Support and Commissions departments at a mid-size consumer products company.  This gave me 10 months of direct, hands-on experience with Zendesk to draw my opinions from.  Currently, I'm working with a small IT Services company to implement Assistly as their ticketing and customer service support system.User ExperienceZendesk looks great in their demo videos, but after using the product we quickly found their user interface to be clunky and counter-intuitive.  The most common complaint from my users was, "Where do I go to make Zendesk do....?"Simple administrative tasks in Zendesk often required multiple clicks before you could take action on the correct item or setting.  Once you finally do something (change a setting, modify a ticket, etc), Zendesk typically leaves you outside of the context of your original workflow.  With no "location breadcrumbs" to let you jump to your original context, you're stuck using the browser's back button, a risky proposition when using web apps.  The alternative is to navigate "back" to your original context by clicking "forward" through the UI all over again.  Very frustrating.In sharp contrast to Zendesk, Assistly's user interface is clean, direct, and intuitive.  Zendesk somehow found a way to make a simple, single-ticket workflow system confusing.  Assistly, on the other hand, lets you work on multiple tickets at once in a clean, easy to understand, tab-based environment.  After suffering with Zendesk for so long, working with Assistly was like a breath of fresh air.WorkflowAs mentioned, Zendesk seems to be built for single-ticket flow, with the emphasis on email, chat, and Twitter inputs.  Assistly also offers these channels, but goes one better by adding intelligent support for phone-based, call center workflows.  Assistly also improves over Zendesk's social media channel by offering tight integration with Facebook pages.  This is an extremely valuable feature, and I'm surprised that Zendesk has not moved more quickly to duplicate it.  There are several posts in Zendesk's forums from users requesting similar functionality, so hopefully it will be added to their platform soon. PricingHere's where Zendesk may have an advantage over Assistly.As far as pricing goes, I used to think that Zendesk's model was confusing and expensive....until I compared it to Assistly. My head is still spinning from reading their "pricing details" page.The good news for those who take the time to digest Assistly's pricing model is that their "a-la-carte" approach allows them to offer an extremely full-featured product at a veryreasonable per-agent price: $49 per month, compared to Zendesk Plus+ at $59 per month.Sounds great, BUT...there's a catch. If you plan on custom-branding the URL of your public Support Center (i.e.support.YourCompanyName.com), AND you want to protect all customer data by securing each connection via HTTPS, Assistly requires you to purchase the "Help Center SSL" option at a cost of $69 per month.Every year, this means that Assistly costs a whopping $708 more than Zendesk.  If you paid Zendesk annually, instead of monthly, the difference jumps to $828.  Ouch!  I could understand a one-time setup fee of $69, but that much every month?  That's quite a premium for something that should be standard on mid-level paid accounts of SaaS apps like this.  Good on you, Zendesk.  You beat Assistly hands-down on this one.Huge Help for Small BusinessesComplaints about the cost of the "Help Center SSL" option aside, I respect what Assistly is trying to do with their pricing model.  They, along with Zendesk, are navigating the transition from traditional Enterprise Software pricing (a.k.a. secretly squeeze every nickel you possibly can from the customer), to a more open and transparent model.  We're not there yet, but the end result of all this will be better products at a lower cost for small and mid-sized companies.Speaking of things that are good for small companies, Assistly does provide one completely free account, with no strings attached.  Knowing that a help desk tends to be more helpful when more than one agent is using it, Assistly created something called a "flex user".  Assistly's customers pay just $1 for each hour that a Flex User uses their ticketing platform.  There is no charge for adding Flex Users, and there is no limit to the number of Flex Users that can be added to an account.  This puts Assistly in reach of many small businesses, despite the cost of some options.On-demand pricing like this is typically offered by PaaS (Platform as a Service) vendors.  I love that Assistly is experimenting with this model for a SaaS product.  I hope to see this idea adopted by other SaaS vendors in the future.And the Winner Is...For me, Zendesk never lived up to expectations in the 10 months I used it.  Although my time with Assistly has been shorter, my experience so far has been great.  Assistly is the hands-down winner over Zendesk in terms of usability, user experience, and workflow.  For my money, if it's a choice between subscribing to Zendesk or subscribing to Assistly, I choose Assistly.Closing ThoughtsAssistly is a very young company, but they've built a fantastic product.  I hope that Salesforce will allow them to keep their fun, quirky, product-driven culture.  If they do, then the massive resources of cash and talent that an organization like Salesforce can provide should lead to fantastic things for Assistly's platform, and their customers.  

Thank you for the opportunity i prefer zendesk

Zendesk is more advanced than Desk.com and has a number of integrations. Its community forums include feedback/upvoting which really help alot. The best part is that it has mobile optimized support website for your customers. Its allows customer to rate your customer support email replies which is not in Desk.com

Thanks for your invitation, Agree on experts answers.

zendesk is one  more comfirtble Helpdesk to promote business on online Chatting

Depends on your main requirements.. Do you need a lot of integration between your CRM, Helpdesk etc? Are you a startup? How many agents are going to be using the product?.. UI and design-wise, Assistly is better than Zendesk (lil bit confusing) and Tender (kind of OK). Whereas integration-wise, zendesk wins and assistly and tender don't offer much.You may also include Freshdesk(www.freshdesk.com) in the list. If you are looking for a simple Helpdesk/Customer support tool that also offers multi brand/multi product support.