Softwr

Cybersecurity · head to head

Authy vs Keil MDK

Authy logo

Authy

Cybersecurity

Twilio's free authenticator app with encrypted cloud backup, mobile only since the desktop clients were withdrawn in 2024.

From
Free
Free plan
Yes
Full reviewWebsite
Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Authy there is no export function for stored TOTP secrets, so moving to a different authenticator means disabling and re-enrolling two-factor authentication on every account individually, which is the reason most users stay rather than a reason anyone should choose it.; Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Authy and Keil MDK actually diverge.

Attributes where Authy and Keil MDK differ
AttributeAuthyKeil MDK
Pricing modelfreefreemium
CategoryCybersecurityDeveloper Tools

Identical on both: starting price (Free), free tier (Yes), platforms (Web), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Authy

  • Encrypted cloud backup
  • Multi-device sync
  • Standard TOTP
  • Offline code generation
  • App lock
  • Multi-device toggle
  • Token organisation
  • Free with no account tier

Only in Keil MDK

Nothing recorded that Authy does not also cover.

What people use each for

The jobs each tool is most often brought in to do.

Authy

  • An individual who wants two-factor authentication on personal accounts and needs it to survive losing or replacing a phonenot Keil MDK
  • A small team sharing access to a service account where the same tokens must be available on more than one handsetnot Keil MDK
  • Replacing SMS-based codes with TOTP for someone who would abandon two-factor entirely if recovery were difficultnot Keil MDK
  • Consolidating tokens scattered across several apps onto one device list with recognisable names and iconsnot Keil MDK

Keil MDK

  • Embedded software developmentnot Authy
  • ARM microcontroller programmingnot Authy
  • Professional development environmentsnot Authy

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Authy

  • There is no export function for stored TOTP secrets, so moving to a different authenticator means disabling and re-enrolling two-factor authentication on every account individually, which is the reason most users stay rather than a reason anyone should choose it.
  • The Windows, macOS and Linux desktop applications were discontinued in 2024 and stopped working, so any workflow that depended on copying codes on a computer now requires a phone in hand, and users who held tokens only on a desktop client had to restore from backup or re-enrol.
  • The account is keyed to a phone number, so an attacker who takes over that number through a SIM swap can begin the device registration flow, and the only remaining control is the backup password that most users set once and cannot recall.
  • In 2024 an unauthenticated Twilio endpoint allowed attackers to confirm which numbers from a supplied list were registered Authy accounts, exposing around 33 million phone numbers, which disclosed no codes but handed phishers a validated list of people known to use two-factor authentication.
  • It is a free consumer application inside a company that has already retired the paid Authy developer API it once supported, so it carries no revenue of its own, and users should treat its continued existence as a business decision rather than a roadmap commitment.

Keil MDK

  • Pricing for Essential and Professional subscriptions not disclosed on primary site
  • Customers must contact Arm Developer Tools store for subscription rates

Pricing, plan by plan

Authy

Free

No published plan breakdown. See the Authy review.

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Which should you pick?

Choose Authy if

  • You need encrypted cloud backup.
  • You want to start without paying.
  • You also want multi-device sync.
Authy review

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Questions people ask

Is Authy or Keil MDK better?
Neither clearly leads. Authy starts at Free and Keil MDK at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Authy or Keil MDK?
Authy starts at Free and Keil MDK at Free.
Does Authy or Keil MDK run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use Authy for free?
Both have a free tier, so you can try either at no cost before committing.
What is Authy best used for?
Authy is most often used for an individual who wants two-factor authentication on personal accounts and needs it to survive losing or replacing a phone, a small team sharing access to a service account where the same tokens must be available on more than one handset, replacing sms-based codes with totp for someone who would abandon two-factor entirely if recovery were difficult, consolidating tokens scattered across several apps onto one device list with recognisable names and icons. Of those, an individual who wants two-factor authentication on personal accounts and needs it to survive losing or replacing a phone and a small team sharing access to a service account where the same tokens must be available on more than one handset are not what Keil MDK is typically brought in for.
What can Authy do that Keil MDK cannot?
Authy covers Encrypted cloud backup, Multi-device sync, Standard TOTP, Offline code generation.

Answered from the vendors’ own pages

Authy: Is Authy still supported?

The mobile apps for iOS and Android are still available and functional. The desktop applications were withdrawn in 2024 and the Authy developer API has been retired in favour of Twilio Verify, so the surrounding product has been shrinking.

Keil MDK: Does Keil MDK have a free version?

Yes, Keil MDK Community Edition is free for non-commercial projects. Essential and Professional editions are available as monthly or annual subscriptions.

Source
Authy: Can I export my tokens?

No. There is no export of the underlying secrets, by design. Migrating to another authenticator means going to each service, disabling two-factor authentication and setting it up again with the new app.

Keil MDK: How much do Keil MDK paid editions cost?

Specific pricing for Essential and Professional editions is not published on the main site. Rates are available from the Arm Developer Tools store or by contacting Arm sales.

Source
Authy: What happened to the desktop app?

Twilio announced its discontinuation in March 2024 and the applications stopped working later that year. There is no replacement desktop client; the mobile apps are the product now.

Authy: Is multi-device sync safe to leave on?

It is the feature most worth understanding. Leaving new device registration enabled means anyone who controls your phone number can attempt to add a device. The usual advice is to turn the multi-device setting off once your devices are registered and turn it on only when you need to add one.

Authy: What if I lose my phone and forget the backup password?

The secrets are encrypted with that password and Twilio does not hold it, so they cannot be recovered. You would fall back to each individual service's account recovery process, which is exactly the situation the backup was meant to avoid.

Share

Related pages

More on Authy

More on Keil MDK

Keep looking

Other head to heads