Best unified inbox apps in 2026
A unified inbox shows all your email accounts (Gmail, Outlook, Yahoo, iCloud, work email) in one list, without merging or moving them. Here are the main options, what they cost and who each one suits. Written by the Kaliham team; we've tried to be fair to everyone, ourselves included.
At a glance
| App | Free with several accounts? | Where it runs |
|---|---|---|
| Kaliham | Yes | Browser, iPhone, Android |
| Outlook | Yes | Windows, Mac, web, iPhone, Android |
| Spark | Yes, with paid extras | Mac, Windows, web, iPhone, Android |
| Mailbird | No, one account free | Windows, Mac |
| Thunderbird | Yes | Windows, Mac, Linux, Android |
| Spike | No, one address free | Windows, Mac, web, iPhone, Android |
Checked November 2026. Plans change, so check each app's website for current prices.
1. Kaliham: free, in the browser and on your phone
Kaliham is a free unified inbox that runs in any browser and installs on iPhone and Android without an app store. It shows Gmail, Outlook, Microsoft 365, Yahoo, iCloud and any IMAP email together, each account in its own colour, and replies go out from the right address. It blocks tracking pictures until you allow them, works with Google Drive for every account, and can connect to Claude or ChatGPT to summarise and draft replies.
Good for: people who want one inbox on phone and computer, free, with nothing to install.
Keep in mind: it needs an internet connection, and it's newer than the others, with no calendar,
snooze or scheduled sending yet.
2. Microsoft Outlook
The new Outlook for Windows, Outlook on the web and the Outlook phone apps can add Gmail, Yahoo, iCloud and other IMAP accounts, and Microsoft has been rolling out an "All accounts" view that shows them together.
Good for: people already using Outlook or Microsoft 365, who also want a calendar.
Keep in mind: the free version shows ads, and non-Microsoft accounts are synced through Microsoft's
cloud.
3. Spark
Spark by Readdle has a "Smart Inbox" that sorts personal email from newsletters and notifications, on every major platform. The free plan includes several accounts; AI features and team tools are paid.
Good for: people who want automatic sorting and lots of features.
Keep in mind: your accounts are connected through Spark's servers, and the best features are paid.
4. Mailbird
Mailbird is a polished desktop program for Windows and Mac with many built-in app integrations. The free plan covers one account; a unified inbox for more needs a paid plan, yearly or one-off.
Good for: computer-only users who like a desktop program.
Keep in mind: no official phone app. See Kaliham vs Mailbird.
5. Thunderbird
Thunderbird from Mozilla is free, open source and has a unified folders view. It runs on Windows, Mac and Linux, and on Android (the former K-9 Mail).
Good for: people who want free, open-source software and lots of settings.
Keep in mind: setup takes more steps, and there's no iPhone app yet.
6. Spike
Spike shows email as chat-style conversations, with built-in team chat and video calls.
Good for: teams who want email and chat in one place.
Keep in mind: the free plan covers one email address, so several accounts need a paid plan.
How to choose
- Free, several accounts, phone and computer: Kaliham, Outlook or Spark.
- No ads and nothing to install: Kaliham.
- Need a calendar in the same app: Outlook or Spark.
- Open source: Thunderbird.
- Desktop program only: Mailbird or Thunderbird.
Questions
Does a unified inbox merge my accounts?
No. Each account stays separate with its own provider. The app just shows them in one list, and replies go out from the right address.
Is it safe to add my email to these apps?
Use the provider's own sign-in (like Sign in with Microsoft) or an app password rather than your normal password, so you can cancel the app's access any time.
Gmail stopped collecting my other email. Will a unified inbox help?
More guides: Kaliham vs Mailbird · Yahoo and Gmail in one inbox · How to create an app password