FairEmail vs K-9 Mail (2026): which should you pick?
As of Nov 13, 2026, K-9 Mail grades higher than FairEmail: 2.8 against 2.4 out of 4.0.
Checked Oct 9, 2026 and Nov 13, 2026 · graded Oct 10, 2026 and Nov 13, 2026 by ToolGPA
K-9 Mail grades higher on the free plan and features. They get the same grade on value for money, ease of use and platforms.
Price, platforms and features side by side. The table says where each price was read and when.
FairEmail
Open source, privacy-oriented email client for Android
Free plan · from $7.49 one-time
Which one is for you
Pick FairEmail if
- Fits if you want an Android mail app with no ads that asks before loading images or links
- Works for people with several accounts at different IMAP or POP3 providers
Look elsewhere if
- Skip it if you also read mail on an iPhone or a computer, as it's Android only
- Not for you if your work mail needs Exchange ActiveSync or Web Services, which aren't supported
- Too light for anyone who wants calendar, contacts and tasks in the same app
- Watch out: the F-Droid build can't reuse a Play Store purchase and has no Gmail quick setup
- Tight if you want AI or translation, as DeepL, OpenAI and Gemini each need your own API key
Pick K-9 Mail if
- Fits if you read several mailboxes on one Android phone
- Works for people who want GPG and open-source code
Look elsewhere if
- Not for you if you use iPhone or a computer, as it is Android only
- Watch out: the site's banner says Thunderbird for Android is the future of K-9 Mail
- Skip it if you need a new address, since it is a client for existing mailboxes
- Tight if you want setup done for you, as you add your own account details
How we grade them
| 2.4GPAFairEmailFair | 2.8GPAK-9 MailGood | |
|---|---|---|
| Value for money | AThe pro features are a one-time $7.49 on US Google Play, covering every current and future one, where email tools here run about $8 a month. Installed from outside the Play Store it's a donation of €7 or more instead, which then covers all your Android devices. | AFree to download under the Apache 2.0 licence, with no paid plans, and a donate link. |
| Free plan and trial | BFree and ad-free with unlimited accounts and addresses, a unified inbox, threading, offline storage and OpenPGP, enough for one person to use day to day. Snooze, send later, reply templates and filter rules are the paid parts. | AThe full app is free from Google Play, F-Droid, GitHub or Amazon. |
| Features | CIt does the mail job: any number of IMAP or POP3 accounts, offline storage, tracking images disabled, PGP and S/MIME, and with pro, snooze, send later and filter rules. The limits are its own: no Exchange Web Services or ActiveSync, and it's mail only, not a calendar or task app. | BPush IMAP, GPG and PGP/MIME, a unified inbox, identities and message tools. The listing shows no gap in the core job of a mail client, though it provides no address of its own. |
| Ease of use | CNo rating on record, and it's a settings-heavy app: PGP runs through a separate app such as OpenKeychain, DeepL, OpenAI and Gemini each need your own API key, and the F-Droid build has no OAuth, so Gmail's quick setup is missing there. | CNo store rating on record. You add your accounts and server settings yourself. |
| Platforms and integrations | DOne operating system: Android phones, tablets and ChromeOS, with no iOS, desktop or web version at all. It connects to most providers over IMAP, POP3 and SMTP, with Gmail, Outlook and Yahoo among them. | DAndroid only: no iPhone, desktop or web version is listed. |
| Best for | private, open-source email on Android | an open-source Android email client |
The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: FairEmail and K-9 Mail. How we grade
Where they differ
- FairEmail is end-to-end encrypted, according to its own site.
- FairEmail can be bought with a one-time purchase.
In commonFree planAndroidOpen sourceEmail client
At a glance
| FairEmail | K-9 Mail | |
|---|---|---|
| Pricing | Free plan | Free |
| Starts at | $7.49 one-time (pro features, US Google Play in-app purchase) | Free |
| Free plan | The app is free without ads: unlimited accounts and addresses, unified inbox, threading, offline storage and OpenPGP. Pro features such as snooze, send later and filter rules are paid. | Free to download from Google Play, F-Droid, GitHub Releases or Amazon; no paid plans are listed. |
| Free trial | None listed | None listed |
| Android | ||
| Made by | FairCode B.V. | K-9 Mail |
| Price read from | play.google.com | k9mail.app |
| Checked | Oct 9, 2026 | Nov 13, 2026 |
Worth knowing
FairEmail
- Supported on Android phones, tablets and ChromeOS only. There is no iOS, desktop or web version.
- Microsoft Exchange Web Services and ActiveSync are not supported; accounts connect over IMAP, POP3 and SMTP.
- The F-Droid build cannot reuse a Play Store purchase and does not support OAuth sign-in, so the Gmail quick setup is missing there.
- It is an email client only: the Play listing says it is not a calendar, contact, task or note manager.
K-9 Mail
- Android only; no iOS, desktop or web version is listed.
- The site's banner says Thunderbird for Android is available now and calls it the future of K-9 Mail.
- It is a client for existing mailboxes and does not provide an email address.
Key features
FairEmail
- Unified inbox for unlimited accounts
- Any number of accounts and email addresses can be added, with a unified inbox, conversation threading, two-way synchronization and push through IMAP IDLE.
- Offline storage and operations
- Messages are stored on the device, and actions taken while offline are synchronized later. The developer states that no data is stored on third-party servers.
- Tracking and phishing protections
- The app asks before showing images or opening links, tries to recognize and disable tracking images, reformats messages and warns when a message could not be authenticated.
- OpenPGP and S/MIME encryption
- Optional end-to-end encryption uses PGP, through the separate OpenKeychain or PGPony app, or S/MIME. Signing and encrypting with S/MIME is one of the pro features.
- Snooze, send later and filter rules
- The pro purchase adds snoozing, sending after a chosen time, reply templates, filter rules, automatic message classification, search indexing and a message list widget.
- Optional translation and AI services
- DeepL translation, LanguageTool grammar and style checks, and OpenAI or Gemini can be turned on in the integration settings. DeepL, OpenAI and Gemini each need your own API key.
K-9 Mail
- Push IMAP
- The feature list names push IMAP support, so new messages can arrive without polling on servers that allow it.
- GPG and PGP/MIME
- The site lists GPG and PGP/MIME support for signing and encrypting messages.
- Unified inbox and identities
- A unified inbox, per-account notifications and multiple identities are listed, along with signatures and BCC to self.
- Message handling tools
- Listed tools include message flagging, keyboard shortcuts, attachment saving and emoji support.
- Several ways to install
- The download page offers the Play Store (with a beta channel), F-Droid, GitHub Releases and Amazon.
Plans
FairEmail
Free$0
Unlimited accounts and email addresses, unified inbox, conversation threading, offline storage and the privacy features. No advertisements.
Pro features (Google Play)$7.49
one-time in-app purchase (US Google Play)
All current and future pro features, including snooze, send later, reply templates, filter rules, S/MIME signing and biometric lock. No subscription.
Pro features (GitHub version)€7 or more
one-time donation
For copies installed outside the Play Store. €7 or more activates pro features on every Android device you own; a smaller donation activates them once.
K-9 Mail
Free$0
Open source under the Apache License 2.0; the site has a donate link.
Common questions
Which is cheaper, FairEmail or K-9 Mail?
As of Nov 13, 2026, FairEmail starts at $7.49 one-time (pro features, US Google Play in-app purchase), and K-9 Mail is free.
Which has a free plan, FairEmail or K-9 Mail?
As of Nov 13, 2026, both FairEmail and K-9 Mail have a free plan.
More comparisons
How this page was made
- The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
- The grades are our own, from each tool’s review or report card. The GPA is their average.
- Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
- The differences and the answers to the questions are worked out from those listings.