Waking up isn't always easy. An alarm clock certainly gets the job done, but not always in the most useful or pleasant way.

Luckily, there's a variety of free online alarm clocks available for almost everyone, and we rounded up seven of the best. As long as you have a computer or a mobile device and an internet connection, you can start using any of these customizable online alarm clocks right away.

If you try a web-based alarm clock in a web browser, make sure your computer or device stays on so that the battery doesn't run out before you need your alarm to go off. Otherwise, you'll be out of luck.

No ads.

Lots of customization options.

Can set only one alarm.

No snooze button.

For a super simple, ad-free, and pleasantly personalized wake-up experience from the desktop, Onlive Clock is our number one choice. The screen shows a digital clock in large numbers over a calm nature scene, which you can change to anything you want by accessing the settings.

Use the drop-down options beneath the time to set your alarm. Select the gear icon at the bottom of the screen to configure your general settings, choose the type of clock you want, choose the color of the numbers, select or upload a background image, and set an alarm sound. Choose from one of the four built-in sounds, one of the built-in radio stations, or a YouTube video of your choice.

As a bonus, you can select the frame icon in the lower-right corner to enter full-screen mode. The clock also looks gorgeous in a mobile web browser.

The only major drawbacks are that you can't set multiple alarms, and there's no snooze button.

You can set more than one alarm.

Large, clear display.

Site offers various other timers and a stopwatch.

Fewer appearance options than some other clocks.

Interface is a bit dated.

TimeMe is our second choice for keeping things simple while integrating several useful features. The TimeMe alarm clock is one of the few clocks that allow you to set multiple alarms—up to 25 that can be color-coded and set on a cycle.

The clock displays large, blue numbers over a white background with a range of settings you can customize beneath it. You're able to check other time zones; give your clock a title; and change the numbers' color, size, and font. To set up multiple alarms, select the Alarms link beneath the clock.

Another great feature of TimeMe is the ability to save your clock settings and grab a link to it for easy access later. The only feature this alarm clock lacks is the ability to customize the background beyond black or white.

Lots of fun options, such as lava lamp and fireplace.

Large variety of sounds; app can choose random sound.

Offers a noise generator with lots of settings.

Can't choose the color or font of digital clock numbers.

Slightly cluttered interface.

No snooze button.

Online Clock is a digital clock that tells the time right down to the second. Beneath the clock, there are a couple of drop-down menu options for setting your alarm. We love this one because of its straightforward yet customizable design.

Select the links beneath the time to choose different clock versions and customize your settings. For example, choose a sound for your alarm, set a timer, start a countdown, or choose a background. Then, use the links at the top of the screen to customize the size of the clock and background color.

Online Clock has a lot of great options if you're looking for something basic. However, its navigation and settings can be a little confusing with all the browser tabs opening any time you make a selection. You also can't set multiple alarms or hit a snooze button, so if those features are important to you, you might need to look elsewhere.

Large variety of alarm sounds.

Snooze button.

Not as customizable as other options.

Ad-supported.

Online Alarm Kur is a simple, no-nonsense alarm clock that tells you the time in digital format over a black background along with the date and alarm settings below it. Set the time you want the alarm to go off, customize the sound of your alarm by choosing from 11 sounds, and set the snooze duration for the snooze button. A countdown will automatically pop up beneath the current time.

Although it works perfectly fine, it's not exactly the most visually appealing due to the large ads that cover up nearly half the screen—nor does it have very many features to customize beyond the most basic alarm settings. And like Onlive Clock and Online Clock, you can only set one alarm at a time.

Optimizes alarm timing for your personal body clock.

Website offers stats and info on sleep.

App for iOS and Android.

No web version.

Annual paid subscription after a 30-day free trial.

Anyone in room snoring and moving can throw off results.

Sleep Cycle Alarm Clock is a free mobile app for iOS and Android, but it doesn't have a web version. What sets this one apart from the rest is that it analyzes your sleep by tracking the sounds from your movement through your mobile device's microphone or accelerometer. Then it selects an appropriate time to wake you up during the light sleep phase of a typical 90-minute sleep cycle.

Set your alarm, and the app will use a 30-minute window around that time to find your lightest sleep state and wake you up. An intelligent snooze feature gives you the option to snooze through your wake-up window. The snooze duration becomes shorter as you're slowly woken up at your desired alarm time. To snooze, double-tap your device.

There's nothing really web-based about this alarm clock except that you need to have internet access to download it.

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Lots of customization settings.

Fall asleep to music while retaining alarm clock setting.

Multiple-alarm capability.

Ad-supported.

Limited selection of alarm sounds.

Alarm Clock HD is one of the best choices for music lovers who are also Apple fans. This handy app transforms your iPhone or iPad into a powerful alarm clock that allows you to set an unlimited number of alarms and wake up to your favorite music from your iTunes library.

To set an alarm, tap the clock icon in the screen's upper-right corner, then tap Add Alarm. You'll be shown several customizable settings for your alarm, including Repeat, Music, Notification Sound, Volume, and Label. You can also take advantage of the Music Sleep Timer in the Settings tab, which allows you to fall asleep to your favorite music.

This app comes with a range of other features that makes it unique, like Twitter integration, local weather information, and customizable clock appearances with unlimited foreground colors.

The only downside is the ads. You can, however, pay for an upgrade to remove them.

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Customizable, with many bells and whistles.

Analyzes sleep patterns and behavior.

No iOS version.

Ad-supported.

Alarm Clock Xtreme is no ordinary alarm clock. Instead, this incredible Android app is a smart alarm clock with features better than all the alarm clocks on this list.

There are several wake-up options. For example, your alarm can slowly increase in volume for a gentle wake-up, play a favorite song from your music library, or force you to solve math problems before you snooze. To prevent yourself from excessive snoozing, set a maximum number of snoozes and set the snooze duration to decrease each time you tap it.

As a bonus, this app doubles ​as a sleep tracker. It can analyze your sleep behavior, identify trends, filter data by weekday, and give you a sleep score based on the data obtained. Like Alarm Clock HD for iOS, Alarm Clock Xtreme's free version has ads, but the premium, ad-free version is available for a paid upgrade.

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Maybe you're wondering if you need an alarm clock. Here are a few situations where an online alarm clock might come in handy even if you already have access to one of the best traditional alarm clocks or a built-in alarm clock app on your mobile device:

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