When comparing Cal vs FastMail, the Slant community recommends Cal for most people. In the question“What are the best calendar apps for Android?” Cal is ranked 4th while FastMail is ranked 14th. The most important reason people chose Cal is:
As long as Facebook is already set up on the device, Cal integrates with it with a single click to show all birthdays.
Specs
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Pros
Pro Can import Facebook birthdays with one tap
As long as Facebook is already set up on the device, Cal integrates with it with a single click to show all birthdays.
Pro Clean interface with beautiful background images
The app displays agenda as a combination of events and to-do list items and uses different background images for each calendar day based on chosen themes.
Pro Integrates with Any.do for task management
Cal integrates with Any.do to-do list app for task management.
Pro Integrates with Waze, Uber and Google Maps for navigation
Cal uses Google Maps to show event location, Waze for real-time traffic information and Uber for hailing a car to the event.
Pro Clean widget with event creation
Cal has a good-looking resizable widget that has a shortcut for event creation.
Pro Nicely designed actionable notifications before, during and after meetings
A feature called HeadsUp will show pop-up notifications on phone's homescreen specifically designed for meetings. The content of the pop-up will change based on whether it's before, during or after a meeting.
Before a meeting it will show shortcuts for getting a taxi or a car, seeing attendees, getting directions and notifying other attendees if the user is late via e-mail or Skype. During a meeting it will give shortcuts for setting the phone on vibrate, taking photos, video or audio-recording, adding tasks that will be synced with Any.do or e-mailing a summary. After the meeting it offers sharing task list and scheduling a follow-up.
Pro Predictive text
While adding an event the app will offer suggestions, help invite other people, pick a location, allow making a note and set it as a recurring event if needed.
Pro Voice entry support
Cal allows adding events simply by speaking.
Pro Traditional revenue model increases likelihood of personal data privacy and safety
Depending on your point of view, requiring to pay for Fastmail is actually a positive aspect of the service. This way you know the company is at least making some revenue (they have been around since 2010) and you know who the customer is. Pricing is as follows (go here for their on-site pricing info).
Pro Human support team
As you are their customer, Fastmail provides human support.
Pro Offers more control over email
Gmail has a tendency to dumb down the interface (try to sort by sender). Fastmail gives full control over email, just like a "traditional" client would.
Pro Secure
Supports two-factor authentication, one-time passwords and fully encrypted connections.
Pro Fully responsive interface
The Fastmail interface is fully responsive across all browser sizes.
Pro Fast
As Fastmail does away with all the extra bells and whistles of Gmail it is super fast to interact with. It also has faster IMAP and SMTP performance than Gmail.
Pro Custom sieve scripts
You can write your own Sieve scripts for filtering/rerouting email.
Pro Simple email actioning
Like gmail, you can "Pin" emails to the top of your inbox to deal with later with either a checkbox or the keyboard shortcut. Like Gmail you can also both archive and delete emails.
Pro Offers IMAP migration tool
Get your old email out of Gmail easily with their migration tool.

Pro Adjustable spam filter
On writing this Fastmail has Basic, Normal, Aggressive or Customisable spam filtering which can be selected in the Advanced settings.
Each user has an individually trainable bayes database to improve spam filtering. You can train your personal bayes database by selecting some messages and using the Report spam and Report Non-Spam options from the Action menu on the Mailbox screen.
For IMAP users who don't use the web interface much, you can specify folders as spam/non-spam training folders on the Folders screen. Then just move messages into those folders as appropriate to train your bayes database.
For your personal bayes databases to be active, you have to train it with at least 200 spam messages and 200 non-spam messages. If you haven't trained enough messages, then we use a global continuously updated bayes database against your incoming messages, which helps detect spam/non-spam, but isn't as good as a personally trained one.
Pro Offers subdomain addressing
Instead of using plus addressing (e.g. foo+bar@email.com), FastMail offers the ability to receive mail through subdomain addresses (e.g. foo@bar.email.com).
Pro Integrated file storage
Fastmail allows saving attachments and other files into their own file storage system for easy retrieval later.
Pro Proper support for folders
FastMail has full support for folders, unlike Gmail where you only have labels.
Pro Intuitive default filters
Fastmail automatically filters your email into:
- All
- Unread
- Personal
- Notifications
- Mailing Lists
Pro Identities & aliases practically gives you a new email that you can manage from a single account
With identities and aliases, you can set up a completely new email address that can be managed from your account, without paying for more. As of time of this writing, FastMail offers up to 500 identities and 600 aliases per account, regardless of plan type.
Cons
Con Cal may give your personal and non-personal information to thrid parties
In the privacy-policy of any.do the following is stated:
"We may share your Personal Information to third parties (with or without compensation) including potential and actual advertisers, sponsors, our third party service providers and partners. We use commercially reasonable efforts to only engage or interact with third parties that post a privacy policy governing their processing of Personal Information."
and
"Use of Non-Personal Information. We may collect Non-Personal Information in order to provide and operate the Service, including for statistical and research purposes; to enable us to further develop, customize and improve the Service based on users’ common preferences and uses; to create and provide our business partners and affiliates with aggregated statistical data and other aggregated and/or inferred Non-Personal Information. We may also disclose Non-Personal Information (with or without compensation) to third parties, including advertisers and partners. We are not aware of the identity of the user from which the Non-Personal Information was collected."
Con Not actively developed any more
Last update was January 2016, and any.do includes a calendar by now.
Con Forces creating an Any.do account
An Any.do account as well as the app has to be used to create tasks, that then will show in the calendar, but cannot be created from the calendar. This can be not only inconvenient but also quite slow.
Con Shallow Any.do integration
Any.do tasks can't be managed from within the app, it requires the user to switch applications.
Con No natural language input support
Cal does not support natural language input, though it may get added in the future.
Con Can be sluggish and buggy
Cal has issues with freezing, sluggishness and other buggy behaviors.
Con Lacks weather information
There is no way to add a weather calendar to the normal calendar view, meaning no weather integration.
Con Australian law enforcement
The company and all email hosted by then is subject to Australian laws requiring sharing with law enforcement. These provisions are weaker than those provided by European GDPR.
Con Lacks folder notifications on official mobile app
Con Expensive
The most popular domain registrars will provide you with both multiple email accounts and a domain name at a lower price than FastMail charges for only 1 email account.
Con Servers are located in the US
Con Not free
