Comparison

Zulip vs Keystone

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Zulip

This app provides organized team chat for groups of any size, enabling users to read and respond to messages in context. It helps maintain focus by allowing users to catch up on topics of interest at their own pace. The application is open-source and available as a cloud service or self-hosted solution.

Highlights
  • Organized team chat
  • Contextual message reading
  • Topic-based conversations
  • Focus maintenance
  • Open-source software
  • Cloud and self-hosted options
Features
Read full description

Zulip (https://zulip.com/) helps teams of all sizes be more productive together, from a few friends hacking on a new idea, to globally distributed organizations with hundreds of people tackling the world's hardest problems. Unlike other chat apps, Zulip lets you read and respond to every message in context, no matter when it was sent. Maintain your focus and then catch up on your own time, reading the topics you care about, and skimming or skipping the rest. Like everything Zulip, this official Zulip mobile app is 100% open-source software: https://github.com/zulip/zulip-flutter . Thank you to the hundreds of contributors who have made Zulip what it is! Zulip is available as a managed cloud service or a self-hosted solution. Please send questions, comments, and bug reports to support@zulip.com, or tweet @zulip.

About

Keystone

Features
Read full description

Keystone gives your projects room to breathe. Keep every project, task, and plan in one calm place, then focus on what matters today. SEE THE WHOLE PICTURE Scan your active projects in a single list. Give each one an icon, priority, and phase. Open a project to work through its tasks, fold completed work away, or archive it when it's finished. PLAN TODAY AND THE WEEK Choose the projects that belong in today's plan and schedule tasks for the day. Move to Week to see each day at a glance, plan ahead, and set recurring work days for a project. A Home Screen widget keeps today's work nearby. CAPTURE WORK QUICKLY Use the command bar to add a task to a project, schedule it for today, tomorrow, or a weekday, and set project priority. You can also add directly from an expanded project. Copy open tasks or share them as a Markdown file when you need them elsewhere. YOUR DATA STAYS YOURS Keystone works offline and syncs through your private iCloud when it's available. Export and import a full data backup from Settings, or save a separate iCloud backup. There is no Keystone account, advertising, or tracking. Built for iPhone. Simple enough to open every day.

Screenshots

Zulip3 screens
Keystone4 screens

Verdict

The call

The clearest difference is update cadence: Keystone at fortnightly against Zulip's monthly. Zulip's advantage is device support (3 vs 1) and iOS requirement (15.0 vs 17.0). On price, ads and in-app purchases there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Zulip ships an update monthly, Keystone fortnightly. The most recent releases landed on October 16, 2026 and October 7, 2026 respectively.

Scorecard3 real differences · 7 level
Zulip versus Keystone: the parameters behind the verdict, then further details
ParameterZulipKeystone
PriceFreeFree
Rating3.7 (16 ratings) — better—
Positive reviews39.3% of reviews—
Number of ratings16 — better—
Update frequencyMonthlyFortnightly — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS15.0 — better17.0
Further details — not scored
Size44 MB4 MB
Age rating12+4+
DeveloperKandra Labs, Inc.Ionut Mocanu

In-app purchases

None

Zulip

No in-app purchases

None

Keystone

No in-app purchases

Questions

Is Zulip free?
Zulip is free to download, with no in-app purchases.
Is Keystone free?
Keystone is free to download, with no in-app purchases.
Do Zulip or Keystone have ads?
Neither Zulip nor Keystone shows ads.
Which is updated more often, Zulip or Keystone?
Zulip ships an update monthly, and Keystone fortnightly. Most recently, Zulip was updated on October 16, 2026 and Keystone on October 7, 2026.

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