Upstream vs Inbox Zero
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Upstream
This AI-powered inbox automatically organizes emails, drafts replies in your unique writing style, and sends follow-ups. It learns your workflow to minimize distractions and ensure no important messages are missed.
- AI email triaging
- Personalized draft writing
- Automated follow-ups
- Self-organizing inbox
- Learns user workflow
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An AI inbox that triages itself, drafts in your voice, and follows up so you don’t have to remember to. ORGANIZE EMAILS YOUR WAY Upstream sorts, flags, and surfaces what needs your attention today. Noise gets filed away. No rules to set up or folders to maintain. It learns how you work and gets out of your way. DRAFTS IN YOUR VOICE. NOT A VOICE. Upstream writes like you. Not like AI pretending to be you. It studies how you write, how you talk to this specific person, and what the thread already sounds like, then drafts from there. The reply is waiting before you've finished reading the email. THE FOLLOW-UP WRITES ITSELF Upstream watches the threads going quiet, writes the nudge, and adds it to your inbox to send. The open loops close themselves. The ball never gets dropped.
Inbox Zero
This AI-powered assistant helps you manage your email inbox efficiently. It prioritizes important messages, drafts replies in your style, and helps you unsubscribe from unwanted newsletters. Automate email handling with custom rules and stay in control of your communications.
- Prioritize important emails
- Draft AI-assisted replies
- Unsubscribe from newsletters
- Bulk archive emails
- Create custom automation rules
- Manage multiple Gmail accounts
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Inbox Zero is a fast, native email app for Gmail and Outlook, with an AI assistant built in. FAST, EVEN OFFLINE Your mail is stored on your iPhone, so your inbox opens instantly and stays usable without a connection. Changes sync in the background. SPLIT INBOX Split your inbox into tabs for the mail you care about. Each tab shows its unread count, so you know where to look first. UNSUBSCRIBE IN SECONDS See who keeps emailing you and choose Keep, Auto-archive or Unsubscribe for each sender, one by one or in bulk. Unsubscribing is free. ASK AI Chat with the Inbox Zero assistant from your inbox or any email. Ask about your mail, or tell it how your email should be handled. NEVER MISS A REPLY Get a notification when an email needs your reply, and tap straight into the conversation. TRIAGE WITHOUT FRICTION Swipe to mark done or read, and jump straight to the next email after you archive. Mark a whole list done at once, and choose your own swipe actions. WRITE AND REPLY Reply inline with attachments, photos and dictation. Drafts show up in your list and open right where you left off. Schedule messages with Send later, and undo a send for 30 seconds. ALL YOUR ACCOUNTS Connect several Gmail and Outlook accounts and read them together or one at a time. BUILT FOR IPHONE A Liquid Glass design, emails that stay readable in dark mode, and remote images loaded through a privacy proxy. Inbox Zero requires a paid subscription. New users receive a 7-day free trial. Monthly and annual plans renew automatically unless canceled at least 24 hours before the end of the current billing period. Manage or cancel your subscription in your Apple ID account settings. Privacy Policy: https://www.getinboxzero.com/privacy Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is in-app purchases: Upstream at none against Inbox Zero's 2. Upstream also leads on iOS requirement (15.1 vs 18.0). On price, update cadence, ads and device support 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
Both are free to download. Inbox Zero sells 2 in-app purchases, starting at $19.99 per month. Upstream asks for nothing beyond the download.
Upstream ships an update every 2 weeks, Inbox Zero weekly. The most recent releases landed on October 24, 2026 and October 31, 2026 respectively.
| Parameter | Upstream | Inbox Zero |
|---|---|---|
| Price | Free | Free |
| Rating | 3.7 (3 ratings) — better | — |
| Positive reviews | 50.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 2 weeks | Weekly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Subscription |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 15.1 — better | 18.0 |
| Further details — not scored | ||
| Size | 87 MB | 35 MB |
| Age rating | 4+ | 4+ |
| Developer | Upstream Labs | Inbox Zero Inc. |
In-app purchases
Upstream
No in-app purchases
Inbox Zero
- Inbox Zero Starter Monthly$19.991 Month
- Inbox Zero Starter Annual$199.991 Year









