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Zero Sum

Zero-based budgeting web and iPhone app with tiered plans and optional bank sync.

Visit Zero Sum

Research-based review, not hands-on testing. Last researched .

Overview

Zerosum is a zero-based budgeting app where users assign every dollar of income to categories, with savings goals, recurring transactions, loan tracking and reports. Plans are tiered by bank-sync level: manual, bring-your-own SimpleFIN/Lunch Flow, or managed sync. It is run as a personal project by one developer in Portugal.

Best for: People who want a zero-based budget, may not need bank sync, and want to pay only for the sync level they use.

Pros and cons

Pros

  • Basic tier ($30/year on the web) includes manual budgeting, goals, recurring transactions, loan tracking, analytics and file import.
  • Bank sync is optional: bring your own SimpleFIN or Lunch Flow account on Plus, or managed sync via Plaid (US/Canada) or Lunch Flow (elsewhere) on Pro.
  • CSV export, JSON budget backups and full account-data export are available on every plan.
  • The vendor says data is not sold, shared for third-party marketing or used to train AI models.
  • Public changelog documents frequent updates; Oct 2026 releases refined credit-card allocation, phone analytics, recurring schedules and shared-budget notifications.
  • Shared budgets include one seat on Basic, three on Plus and five on Pro.

Cons

  • Very new product with a short public history; the App Store listing currently shows 30 ratings.
  • Terms describe it as a personal project run by one person, with no uptime or support guarantee.
  • Native app is iPhone-only; Android, Mac and Windows use installable web apps, which require an internet connection.
  • No free tier; the one-month Pro trial requires a payment method and renews at $75/year unless canceled.
  • iOS in-app prices are higher than website annual prices (Basic $39.99 vs. $30; Plus $59.99 vs. $50; Pro $89.99 vs. $75).
  • Managed bank sync is limited to Plaid in the US/Canada or Lunch Flow elsewhere.

Features

  • Envelope budgeting not confirmed not confirmed
  • Automatic bank sync included
  • Manual transaction entry included
  • Goal tracking included
  • Debt payoff tools not confirmed not confirmed
  • Investment tracking not confirmed not confirmed
  • Bill reminders not confirmed not confirmed
  • Reports & charts included
  • Multi-currency not confirmed not confirmed
  • Shared / household budgets included
  • Separate logins for shared budgets not confirmed not confirmed

Zero-based budgeting, savings goals, recurring transactions, split transactions and transfers, loan and mortgage tracking, analytics dashboards, bank sync options, shared budgets, 17 themes

Our review

Short version

Zerosum is a zero-based budgeting app where users assign every dollar of income to categories, with savings goals, recurring transactions, loan tracking and reports. Plans are tiered by bank-sync level: manual, bring-your-own SimpleFIN/Lunch Flow, or managed sync. It is run as a personal project by one developer in Portugal.

Quick profile, not a full review. Updated 2026-10-15 from the vendor site, help center, changelog, store listing and public sources. No hands-on testing: I did not sign up, start a trial or connect a bank.

Cost

  • Web plans: Basic $30/year, Plus $50/year, Pro $75/year; prices are before tax.
  • iOS in-app annual prices: Basic $39.99, Plus $59.99, Pro $89.99. Monthly prices are $5.99, $8.99 and $12.99, respectively.
  • Trial: one month of Pro Annual, payment method required; renews at $75/year unless canceled before the first payment.

What is distinct

  • Tiered plans price bank-sync access separately, including bring-your-own SimpleFIN/Lunch Flow sync.
  • Multiple tags per transaction; customizable analytics dashboards and built-in reports.
  • 17 color themes, with light and dark variants.
  • Native iPhone app; Android, Mac and Windows use installable web apps (PWA).
  • Auto Budget panel can fill underbudgeted categories or cover overspending.
  • Recent public updates include improved credit-card allocation rules (v1.10.6, Oct 5) and shared-budget notification controls and analytics/recurring-transaction refinements (v1.10.7, Oct 11).

Not confirmed

Exact founding year; Android/Google Play native app (the vendor says there is no Android app); independent review base beyond the App Store; debt payoff, bill reminders and investment tracking; multi-currency conversion (each budget has its own currency).

Notes

The website lists 16 built-in reports; the App Store description says twelve. App Store listing showed 30 ratings (5.0/5) when checked; that is a small sample. The vendor's installation guide says the PWA requires an internet connection.

Ratings are set separately against a shared rubric.

Sources

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