In this day of modern computers, smartphones, and apps, digital calendars have become incredibly user-friendly. You can sync a calendar across any operating system, get a calendar app for free on your smartphone, and even set up communal calendars with your family, friends, or colleagues.

But that's not to say that digital calendars don't have their downsides.

A calendar on your computer can be just as difficult as a paper calendar (some of us prefer planning schedules on paper) to keep straight or organized, especially if you have a particularly busy schedule.

Luckily, there are plenty of applications and websites that can help you keep on top of everything in your schedule. Here are five tools that can be particularly helpful for keeping your calendar in order, and they're all free!

Cozi -- A Slick Calendar for Every Family

Cozi Calendar Interface

This family-oriented application has one of the easiest-to-use calendar interfaces on the web, and it is also one of the most useful for a family. From a simple vertical interface, reminiscent of the old family planners, you can plan meals, keep track of school events or local calendars, and keep color-coded weekly or monthly appointments.

Cozi Calendar

Cozi is intended to be a shared family app, a sort of digital replacement of the calendar or to-do list taped to the front of the refrigerator. In addition to its communal calendar, Cozi has a grocery list, a checklist, a meal planner, and a family journal.

The to-do list is probably one of the more useful features, especially for those of you who need help managing those kinds of lists.

Cozi Meal Planner

One of the main benefits of Cozi, for a family or group, is that it can import calendars from elsewhere and integrate them into Cozi's calendar. This includes your Google Calendar, naturally, but also various other online calendars such as those used by schools and event centers. Cozi also includes detailed instructions on how to import the calendar to yours.

Cozi Calendar Integration

Most of the calendar's more desirable features are available in the free version. A Cozi Gold upgrade unlocks power features like multiple reminders, birthday trackers, and a shopping mode. Cozi is also available in mobile form, meaning you can manage your family calendar, and all of the other features, from your phone or tablet. It is available for iOS, Android, and Windows phones.

Assistant.to -- Schedule Meetings Easily

Assistant.to Successful Scheduling

This Google Chrome add-on does only one job, but it does that job very efficiently. It is an extension that works within your Google Calendar and allows you to schedule meetings with time slots within your e-mails and integrate them seamlessly into your calendar.

Assistant.to Schedule in Email

When you open an email draft, press the "A" button in the bottom of your email. This will bring up a schedule from which you can select up to three blocks of time. When you are done, these time slots, along with the meeting's name and location, will be automatically inserted into the body of the email.

Assistant.to Insert into Email

When the person you sent the email to accepts one of these times, the meeting is automatically inserted into your Google Calendar (and theirs, if they also have Assistant.to) and you will receive a confirmation email.

Assistant.to Calendar Meeting

If you keep your schedule primarily within Google Calendar, then Assistant.to can be a great help in keeping everything straight. It also saves you the trouble of remembering to put meetings into your schedule.

Assitant.to works a lot like Google Calendar's own appointment slots. Set up appointments on your calendar that people can reserve. Appointment slots only work with Work or School Google Calendar accounts.

YouCanBook.Me -- Let Others Schedule Your Time

YouCanBook.Me Calendar

Many of these apps are made essentially for private use, or at least those for business are made with office work or bureaucracy in mind. But suppose you are a business owner who takes clients by appointment, and you want people to be able to book parts of your time in such a way that is convenient for both of you. YouCanBook.Me is possibly the easiest tool available for that, and it's incredibly easy to both set up and use!

YouCanBookMe Setup

You can make a YCB via iCloud, Google, or Facebook accounts. Setting up your account is as easy as entering a name, company title, and sector (I picked one the one above just for the giggles). After that you can select a custom URL based on your company name, your name, or your sector.

YouCanBookMe Settings

Once you have run through the setup, your booking calendar is fully customizable to your needs. You can select what times you are available, what kind of confirmation and reminder emails to send, and what kind of information your client needs to provide a booking.

There are some deeper kinds of customization available to users who get premium accounts, but the basic package is still pretty impressive for an individual or a small business.

YouCanBook.Me Booking

Your booking page can also be embedded onto your webpage or you can embed a button linking to your YCB page. Either way, it's incredibly convenient for the business owner and makes things very easy for your clientele.

Doodle -- Scheduling Simplified

Doodle.com Main Screen

Doodle is probably the most aesthetically bare and stripped-down option available on this list. Its features and functions are limited, but it is good for a creating a schedule with which your clients and/or colleagues can interact.

Doodle.com Calendar Poll Function

Doodle can be used without an account, though only the most basic function of creating a poll is really available or feasible to use without an account. Create an account for using the other features.

Doodle allows you to create unlimited polls. The calendar select function within the poll settings can make it a good tool for helping to schedule events. You can select allotments to put in a poll, allowing people who can see the poll to vote on appropriate times for a meeting or anything else.

Doodle.com MeetMe Calendar Tool

There is also a feature called MeetMe, which provides a Doodle URL that makes scheduling easier. In much the same way as YouCanBook.Me, it provides a calendar for your visitors, and they can mark the times they would like to meet you in a request. You can link your Google, iCloud, and Outlook calendars so that anyone can see when you're available.

Doodle.com Scheduling Tool

While not as customizable and convenient as YCB, Doodle is still a useful and easy-to-integrate tool, especially for those who use Google Calendars. Doodle is free for one user. The Premium and Business features give you advanced options like secure encryption and are free from ads.

Need to be reminded to keep your appointments? Google Reminders is available now to keep you on schedule and help you complete your tasks.

Calendly -- Frictionless Scheduling

Calendly Main Page

If you look at YouCanBook.Me and Doodle above and believe those are inadequate for your scheduling needs, then Calendly might be the solution you're looking for. It is a happy marriage between the two, and provides a bit more privacy than both.

Calendly Invite Meeting Suggestion

The person scheduling with you cannot see what blocks of time are already taken or why. Instead, they select from available blocks, the time intervals between which you can customize. They must provide at the very least their name and address, and you can specify how you are to be contacted and how long the meeting can last.

Calendly Day Time Settings

On the settings page, you can specify what kind of events you can be invited for, from the name to the duration, to the specific days and times available. If you are using Google Calendar, you can also specify in the settings which calendars Calendly should check for conflicts. From your Calendly dashboard, you can see who has requested a meeting and when.

Calendly Confirmed

Calendly allows you to schedule meetings that mesh with your day-to-day schedule by working with your Google Calendar, and not interfering with events you make yourself on the same calendar.

Want to sync your calendar between your Linux system and your Android device? That is possible too!

How Do You Keep Your Schedule Organized?

Calendars don't come alone anymore. There are scheduling apps and Google Calendar third-party tools that make time planning painless. Try them out even as you review your own priorities and objectives.

Do you use any special web apps or tools for keeping your calendar in order? Let us know about any good ones we may have missed in the comments section below!

Image Credits:Paper calendar by Sarunyu_foto via Shutterstock