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The best cloud backup services in 2021

Best Cloud Backup Services
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The best cloud backup solutions help you avoid data disaster. Each periodically copies your personal data to far-off cloud storage servers that can be reached from anywhere.

This is essential, because you can't always count on local backups to protect your data. An external hard drive attached to your PC, or on your home network, may fall victim to the same flood, fire or theft that takes out your computer, leaving you with nothing.

Many businesses turn to "off-site" backups to minimize the threat of physical disasters. Cloud-backup services provide this to consumers.

Each cloud backup service we've tested — Acronis True Image, Backblaze, Carbonite Safe, CrashPlan for Small Business, IDrive Personal and SpiderOak One — uses industry-standard encryption on their own servers to protect your data. 

Each service also lets you encrypt your data with your own private key. But if you lose that key, the service can't help you recover the data.

Top 3 best cloud backup solutions

1. IDrive is the best cloud backup solution right now

1. IDrive is the best cloud backup solution right now
IDrive ranks highly on every review due to its great features and fair pricing. The software is available for Windows, macOS, Android and iOS, and there are command-line scripts for Linux machines.

2. Backblaze is the easiest cloud backup solution

2. Backblaze is the easiest cloud backup solution
Backblaze is the easiest cloud storage solution to use  — just set it and forget it. It has a useful restore-by-mail feature and rapid upload speeds. This is a great choice if you're looking for the best bang for your buck.

3. Acronis True Image is a powerful and versatile option

3. Acronis True Image is a powerful and versatile option
Acronis True Image, recently renamed as Acronis Cyber Protect Home Office, is the most powerful online-backup solution available for consumers, and now includes antivirus software and ransomware protection.

Some cloud-backup services let you back up operating-system files and applications, while others back up smartphones and tablets. Most can back up files to a local drive, and some even let you share files with other people or provide file-syncing or dead-storage functions. 

Because restoring terabytes of lost data can take days, some of these services will express-ship you a hard drive with your recovered data to save time.  (IDrive also lets you "seed" an initial backup in the same way.)

News & Updates

— Carbonite has slashed prices by 40%, bringing the price of its entry-level subscription plan to $50 per year.

— Acronis announced that Acronis True Image will henceforth be known as — deep breath — Acronis Cyber Protect Home Office.

But while some of these services back up an unlimited number of devices, and others give you unlimited online storage, none gives you unlimited space for an unlimited number of devices for a single flat price. That would just be too good to be true. 

One last thing: Cloud backup services aren't always the same thing as cloud-based file-syncing services like Dropbox or Microsoft OneDrive. Nor are they exactly like file-archiving services such as Amazon Glacier. We explain the differences between these categories at the end of this buying guide.

Get Backblaze for free with every ExpressVPN purchase

Get Backblaze for free with every ExpressVPN purchase
ExpressVPN, Tom’s Guide’s #1 VPN provider, is offering free unlimited cloud storage courtesy of Backblaze for a whole year with its annual subscription. Secure, business-grade online backup for everyone, no strings attached.

What are the best cloud backup services?

Based on our testing, our Editor's Choice is IDrive ($3.98 for the first year for Tom's Guide readers). It backs up an unlimited number of PCs, Macs, smartphones and tablets for a reasonable price. IDrive is the best choice if you have multiple computers and phones.

Our value pick is Backblaze, which gives you unlimited storage for just $70 per year but backs up only one machine (and an external drive) per subscription. This is the best cloud backup service if you have a single Mac or PC and don't want to worry about the details.

Acronis True Image is best for power users, offering a breathtaking assortment of useful features. It's rather complicated and can get expensive for the average home computer user, but it gives you more options than you can possibly think of.

CrashPlan for Small Business technically isn't for home users and costs $10 per month per machine. You'll get an unlimited cloud backup space, extensive security and scheduling options and very fast speeds. However, you won't get mobile-device backups or any drive-shipping options, and CrashPlan's networked-drive backups don't work on Windows.

SpiderOak is famed for its security and encrypts your data with a unique key that only you have. (Don't lose it.) Subscriptions are quite pricey, so get SpiderOak only if protecting your data from prying eyes is your top priority.

Carbonite was once synonymous with cloud-backup software, and it still has a rich feature set. Its consumer offerings seem affordable, but read the fine print: To get anything like iDrive or Backblaze's level of service, you'll have to pay more.

External hard drives stacked on top of laptop. Best cloud backup review

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The best cloud backup service you can get today

Best cloud storage service: IDrive Personal best cloud backup review

(Image credit: iDrive)

1. IDrive Personal

The best cloud storage service overall

Number of devices: Unlimited
Storage limit: 10TB
External drive backups: Yes
Mobile device backups: Yes
System and application backups: Yes, but not by default
Two factor authentication: Yes, via email
Drive shipping: Seed and restore
Reasons to buy
+Free disk-shipping data-transfer option+Fast upload speeds+Backs up mobile devices+Generous syncing option
Reasons to avoid
-No unlimited storage option

IDrive offers the most bang for the buck, backing up an unlimited number of machines to either a 5TB ($3.48 for the first year for Tom's Guide readers) or a 10TB limit, which should be enough for most people. It's our Editor's Choice for best cloud backup service.

IDrive's upload speeds are fast, its mobile apps actually back up the devices they run on (and recognize faces in photos for easy tagging), it provides a generous file-syncing option and it even lets you mail in a full drive instead of spending days uploading data. 

IDrive also keeps old copies of each file forever, which is handy, but you'll have to mind those storage caps. It also has two-factor authentication, which is an essential feature every online service provider should offer.

Read our full IDrive Personal review.

Backblaze best cloud backup review

(Image credit: Backblaze)

2. Backblaze

The best value in cloud storage services

Number of devices: 1 computer
Storage limit: Unlimited
External drive backups: Yes
Mobile device backups: No
System and application backups: No
Two factor authentication: Yes
Drive shipping: Restore only
Reasons to buy
+Cheap, fast, easy and simple+Unlimited storage+Generous drive-shipping policy
Reasons to avoid
-No multiple-computer plans-Mobile apps could be better

Backblaze is one of the cheapest cloud-backup solutions, gigabyte for gigabyte, and that's despite a recent price hike. It's definitely the easiest to use — you literally can just set Backblaze and forget it. 

We also like the generous restore-by-mail feature and its rapid upload speeds. Backblaze even lets you locate a lost or stolen computer by geolocating the Wi-Fi network it connects to.

But Backblaze is starting to be left behind as competitors add features such as cloud syncing, file sharing and backups of networked drives. It's also not ideal for anyone who has multiple machines to back up, unless you happen to have have nearly unlimited storage needs. In that case, the reasonable yearly cost to back up each machine may be worth multiple Backblaze subscriptions.

Read our full Backblaze review.

Acronis True Image best cloud backup review

(Image credit: Acronis)

3. Acronis True Image

The best cloud storage service for power users

Number of devices: Up to 5 computers; unlimited mobile devices
Storage limit: 5TB
External drive backups: Yes
Mobile device backups: Yes
System and application backups: Yes
Two factor authentication: No
Drive shipping: No
Reasons to buy
+Very extensive, powerful, unique feature set+Extremely small system-performance impact+Modern, intuitive user interface
Reasons to avoid
-Can get incredibly expensive, with complicated pricing-Home users won't need many of the features

Acronis True Image, recently rebranded as "Acronis Cyber Protect Home Office,"  may be the most powerful and versatile online-backup solution available, with a terrific desktop application and an insane number of backup and security options. 

It offers mobile-device, external-drive and social-media backups, as well as syncing and sharing options. It will save an image of your primary hard drive — applications, OS and all — to the cloud. It also includes antivirus software, ransomware protection, a vulnerability scanner and a bootable file-restoration tool. 

Yet Acronis True Image/CPHO can be the most frustrating of the best cloud backup services, with prices that rapidly ratchet up as you add devices and storage, and weak web and mobile interfaces. But may be the best option if you're a power user or someone who's shopping for antivirus software as well.

Read our full Acronis True Image review.

CrashPlan for Small Business best cloud backup review

(Image credit: CrashPlan)

4. CrashPlan for Small Business

Number of devices: Unlimited, priced per machine
Storage limit: Unlimited
External drive backups: Yes
Mobile device backups: No
System and application backups: Yes, but not recommended
Two factor authentication: Yes
Drive shipping: No
Reasons to buy
+Unlimited storage+Fast upload & download speeds+Lots of security and scheduling options
Reasons to avoid
-Rather expensive-Resource-hungry during backups

CrashPlan had the best cloud backup service for consumers until it quit the market in 2017. Its plan for small businesses retains that service's very fast upload and download speeds, and adds business-friendly features such as support for Red Hat and Ubuntu Linux and unlimited (if you want) retention of old versions of files.

Almost everything is customizable, including frequency of backups, retention of deleted files, account security and where to download restored files. CrashPlan supports full-drive-image backups to local drives and backs up Linux/macOS-formatted networked drives. And you get unlimited backup space for unlimited devices as long as you're willing to pay $10 per month per computer.

What you won't get are the consumer-friendly features that made CrashPlan for Home so appealing, such as drive shipping and mobile-device backups. The mobile apps have great security but are pretty bare-bones. CrashPlan for Small Business also consumes a fair amount of system resources during backups, but you can adjust the application settings to reduce that.

Read our full CrashPlan for Small Business review.

SpiderOak One

(Image credit: SpiderOak)

5. SpiderOak One

Number of devices: Unlimited
Storage limit: 5TB
External drive backups: Yes
Mobile device backups: No
System and application backups: Yes, but not by default
Two factor authentication: Only for legacy users
Drive shipping: No
Reasons to buy
+Backs up unlimited devices+Strong sharing and syncing features+Focus on security
Reasons to avoid
-Steep learning curve-Cramped, confusing user interface

SpiderOak was the first online storage (or online-syncing) service to make sure the customer held a private, exclusive encryption key. 

Most other cloud storage services now offer the same thing, but SpiderOak also has strong file-sharing and -syncing features, as well as support for unlimited machines and, if you insist, backups of system files and applications. 

Yet SpiderOak's storage-space pricing is so high that it's more competitive with Dropbox than it is with IDrive. While its file-restoration speed was amazingly fast, its initial upload speed was glacial.

Read our full SpiderOak One review.

Carbonite Safe

(Image credit: Carbonite)

6. Carbonite Safe

Number of devices: Up to 5 computers, priced per machine
Storage limit: Unlimited
External drive backups: With Plus or Prime plans
Mobile device backups: No
System and application backups: No
Two factor authentication: Yes
Drive shipping: Restore only
Reasons to buy
+Unlimited storage+Intuitive backup-flagging system
Reasons to avoid
-Desirable features cost extra-Slow upload speeds-Mobile apps no longer available

Carbonite offers unlimited storage, which is always nice to have in one of the best cloud backup services. It also has an intuitive user interface that shows you which files have been fully, partly or not backed up.

But you'd better read the fine print, as Carbonite doesn't automatically back up large files, external drives, or any kind of video file on its Basic pricing tier. To get those functions, you'll have to trade up to the Plus or Premium plans, which have features similar to IDrive or Backblaze's basic plans but cost much more. (Carbonite has temporarily slashed prices by 30%, bringing costs a bit closer to those of its rivals.)

Multiple machines are supported on a single account, but there's no volume discount — each additional machine costs as much as the first. Upload speeds are slow. And Carbonite's appealing mobile apps are no longer available, with the company giving no timetable for their return.

Read our full Carbonite Safe review.

How we test the best cloud backup services

We took into consideration several factors: storage costs, ease of file restoration, computer-resource usage, unique features and ease of use and of installation. Upload speed also matters, because while your initial backup happens only once, the backup can take days or even weeks if it's several hundred gigabytes. 

We give bonus points to those online backup services that let you mail in a hard drive full of data to start the process or send you one to restore your data.

Our testing and evaluating was done on a 2017 15-inch Apple MacBook Pro booting into Windows 10. Mobile apps were run on a Google Pixel XL 2 running Android 8.1 Oreo. We monitored data-transfer rates on the MacBook with GlassWire, and CPU usage using Windows' built-in Resource Monitor.

Each cloud backup service was tested individually, then uninstalled from both devices before the next test. The test set of files to back up consisted of 16.8GB of documents, photos, videos and music. We uploaded this data to each service's cloud servers, then restored a 1.12GB subset of these files to the laptop.

The testing environment was a home in Middleton, Wisconsin, provisioned by TDS Telecom Extreme 300 Fiber internet service. Internet speeds during testing were typically 280 megabits per second (Mbps) down and 120 Mbps up, according to

Online backup vs. online syncing vs. online archiving

Cloud-backup services aren't the same as online-syncing services like Dropbox, Google Drive, iCloud or OneDrive

An online-syncing service's software creates a cloud-based mirror of a specific set of files or folders on your device, and pushes out identical copies of those files to all of your linked devices so that you can have immediate access to them. Think of the syncing service as the hub on a spoked wheel, with all your linked devices at the ends of the spokes.

Network cables plugged into servers.

(Image credit: asharkyu/Shutterstock)

Cloud-backup services are simpler. They continuously or periodically copy all or most of the files and folders on your computer to their own cloud servers. Instead of the spoked-wheel diagram of a file-syncing service, an online-backup service would look like a straight line between your machine(s) and the cloud server. 

Your data stays on those remote backup servers until you need it, and with luck, you never will. Most cloud-backup services offer generous amounts of storage for a subscription fee that is much cheaper, gigabyte for gigabyte, than an online-syncing service.

Cheapest of all are cloud-archiving services such as Box or Google Cloud. These let you offload files you don't immediately need to online servers, freeing up space on your hard drive. 

Cloud-archiving services can be dirt-cheap, sometimes as little as a few pennies per month per gigabyte, but there's often a fee to download files again. (The assumption is that you will never need to download all the archived files.) Backblaze has its own very affordable cloud-storage service called B2.

Paul Wagenseil

Paul Wagenseil is a senior editor at Tom's Guide focused on security and privacy. He has also been a dishwasher, fry cook, long-haul driver, code monkey and video editor. He's been rooting around in the information-security space for more than 15 years at, SecurityNewsDaily, TechNewsDaily and Tom's Guide, has presented talks at the ShmooCon, DerbyCon and BSides Las Vegas hacker conferences, shown up in random TV news spots and even moderated a panel discussion at the CEDIA home-technology conference. You can follow his rants on Twitter at @snd_wagenseil.

  • rocker60
    One needs a careful warning for iDrive. As a customer, I can say that their customer service will infuriate you. Here's the scenario:

    Had less than 5 TB to image for the iDrive Express service (i.e. included in pricing package). If you're a non-techie, you won't know that there is less than 5TB available on the 5TB Express Drive. Or... you just forget. Or you're "close", and figure you'll try it out. So you order the 5TB drive. Not big enough. Send it back.

    Upgrade to 10 TB because they won't send you a 10 TB Express Drive unless you sign up for the 10 TB service. Order 10 TB Express Drive. Won't send it to you free because you've already used your "one free per year". Send you a note to ask why you sent back an empty Express Drive and if you really meant to do that. Reference trouble ticket notes. No response.

    After one year. Request 10 TB drive to backup what is now 5.88 TB. Should be okay, right? Nope. Fails. 9.1 TB available isn't enough to do encrypted imaging on 5.88 TB because the encryption needs space to generate temporary files that are then deleted from your Express Drive. Total space needed? 11.3 TB. Told by support to send in 10 TB drive and order 20 TB Express Drive referencing technical support notes on ticket. Request for 20 TB drive denied. Why? "You have to upgrade to 20 TB storage to get a 20 TB drive."

    What...the...heck. So you want me to pay for 20 TB of storage to store 5.88 TB because y'all can't get your crap in a group and read trouble tickets and make a sane judgement? Company appears to be run out of a call center in India. No particular help from support or sales team. No one at iDrive who has a brain and the ability to actually just put a hard drive in a box to make a customer happy.

    BEWARE! iDrive support is horrible. Not sure what it would be like if I ever need to get a backup. At which point, I'm probably already going to be irritated, so probably not the best time to haver someone holding your data hostage. Caveat emptor, here, y'all. Each function is divided up into a "department" and "departments" don't/can't/won't talk to each other. Service promises much. Can't deliver on simplest functions of that.
  • ewolsh
    I agree about I-Drive.
    I also find BackBlaze problematic. I would say, it is not ready for prime time. The calling card seems to be the ease of use?, and lack of set-up required.? It's the little things, 1) The first time you want to recover a files your generated file list appears on a part of the screen that is not visible. You are looking at a black page- ESP helps to figure out what is going on. 2) no set up? that's great until they tell you - oh, they don't have any of your emails. .pst files aren't part of their saved files. They expect you to know this, because you are expected to have worked your way through their detailed set-up instructions, which are just as complicated as everyone elses. 3) Cuntomer service is only occationally available. And now it is email only. They used to have phone techs, some of whom were actually rude, With the nice ones, each one would tell you something different. Now with the e-mail, on a weekend, you have to monitor your email until they respond. That means you have found an alternative solution and the e-mail is irrelevant when it arrives. The answer chat bot is useless, it is easier to search the site yourself- you get the same or better answers... and then there was the time my hard drive blew up and I wanted to save it. I even payed extra to save it, but someone at BackBlaze just changed the name of the new computer, to the old computer name, and the additional saved hard drive disappeared. Luckily I was able to save oldhard drive- or I would have complained to who? Now I'm trying to get the account closed. Wish me luck.
    I miss Mozy!
  • Pramodius
    Beware of iDrive - they are the most untrustworthy of all the backup providers our there. While it sounds like an amazing deal to use their iDrive or iBackup products, because they are so cheap, this is a classic bait and switch policy. I signed for 500 Gb of backup space - and accidentally use 750Gb of backups for less than 24 hours. They kept on allowing the backup to run, and instantly debited my credit card with a $450 charge, because they charge you $3 for 500Gb, then $2 per Gb over !!!! This was for going over the limit, instead of just blocking the backup. They make their money by having the most unbelievably crooked business model. I would avoid them like the plague. Rather pay a bit extra - you go over your limit with them and you'll get charged thousands of dollars WITHOUT ANY NOTICE!!! They are outright crooks.
  • TomsFactChecker
    Well Tom, you completely missed the boat here. has been horrible. The affordable annual fee has led to substantial fraudulent and unauthorized usage charges from the iDrive company. The idrive app does not display folder sizes so one can not tell where backup capacity is being used. Furthermore, there is nowhere in my account to delete the credit card. Finally, their customer disservice department was completely unhelpful and refused to remove the unauthorized charges even stating that there will be more charges if I do not manually delete backed-up data each month. Just another scam. I used Tom's Guide to pick IDrive and now I regret both choices.
  • AlJohnson
    Used the free version for a few months with no problems and then bought the 5TB plan and the problems started.
    I began with the free version, and that seemed to work OK. Switched to the 1 year 5TB discount plan about a year ago. Here is a list of problems:
    Support never responds to website requests for support.
    Error messages are nebulous. For example:a. "Failed to continue the Backup operation. Reason: There are no files to backup]"
    If there are no files to back up, why is that a failure?
    b. Some files could not be backed up because of an unexpected error". However, the unexpected error is never explained. How is the user to know which files encountered unexpected errors?
    I would think that when I have to reboot during a backup, instead of getting an error that the backup failed, there would be a continuation from where the backup left off, but I have never seen anything like that. Instead, the backup starts again from the beginning.
    Sometimes when I reboot or do an update, instead of my mapped drives being shown in the bottom pane, iDrive changes them to the upper pane without notifying me. I have to uncheck those drives in the upper pane and then close the change box and only then will the mapped drives appear in the bottom pane.
    In the logs under 'Operation', the mapped drives are not specified. Why not call the backups operations of the mapped drives, "Mapped Drives"?
    Backups are very slow. I have a 1GB down/500MB upload connection, which I have tested with many broadband speed tests, but backing up, for example, 180GB on my mapped drives, can take 2-3 days. I have the throttles set to between 85-100%.My OS is Windows 10 on an ASUS VIVOBook S15 with 20GB RAM

    I have reported all of these, but never got an answer except once...telling me to go to the support page where I posted all the above but never got a response. 'iDrive support' is an oxymoron in my experience.

    Have cancelled renewal and will look for alternatives.