Trout vs Firefly III
Firefly III is a double-entry bookkeeping tool. Trout is an envelope budgeting app. Both are open source with self-hosting options. Trout also offers a free hosted tier. Different tools for different problems.
Different tools for different goals
Trout
Plan before you spend
Assign income to categories. When you go to buy groceries, you see exactly how much is left in that envelope. If one category runs low, move money from another. The budget drives your spending decisions.
Firefly III
Record what you spent
Every transaction is a debit from one account and a credit to another. You see exactly where money went after the fact. Great for accounting accuracy, tax prep, and understanding spending patterns over time.
If you want to control future spending, envelope budgeting (Trout) is the right fit. If you want precise records of past spending, double-entry (Firefly III) is the right fit. Some people use both.
Feature comparison
| Feature | Trout | Firefly III |
|---|---|---|
| Budgeting Method | Envelope / zero-based | Double-entry bookkeeping |
| Pricing | Free / Pro from $5/mo | Free (self-host only) |
| Hosted Option | ||
| Open Source | FSL-1.1-MIT | AGPL-3.0 |
| Self-Hosted | ||
| AI Assistant | Pro | |
| Bank Sync | Pro (GoCardless Open Banking) | Via data importer |
| Crypto Tracking | ||
| Multi-Currency | ||
| Transaction Rules | Advanced (AND/OR) | Basic |
| Recurring Transactions | ||
| Reports | ||
| API | REST + Eden Treaty | REST |
| Database | PostgreSQL | MySQL/PostgreSQL |
| Backend | Elysia (Bun/TypeScript) | Laravel (PHP) |
| Frontend | Next.js 15 + React 19 | Blade + Vue |
| Docker |
What Firefly III does better
Accounting rigor
Double-entry bookkeeping means every dollar is accounted for on both sides. If numbers do not balance, something is wrong. This level of accuracy matters for tax prep, business expenses, and anyone who needs an audit trail.
Maturity and ecosystem
Firefly III has been around for years with 17,000+ GitHub stars, dozens of third-party tools, mobile apps, and a large community. Trout is a newer project with a growing community and fewer integrations than established tools.
Flexible import pipeline
Firefly III's data importer handles CSV, Spectre, and various bank formats. The import configuration is detailed and customizable. Trout relies on GoCardless for bank sync and does not support manual CSV import yet.
Database choice
Firefly III supports both MySQL and PostgreSQL, giving you more flexibility in how you deploy. Trout requires PostgreSQL.
What Trout offers differently
Proactive budgeting
Trout's envelope method tells you how much you can spend before you spend it. You allocate income to categories and see available balances in real time. Firefly III tracks spending after the fact -- it will tell you that you overspent, but not prevent it.
AI assistant
Ask questions about your finances in plain English. "How much have I budgeted for food?" or "What did I spend at restaurants this quarter?" The AI queries your actual data. Firefly III does not have AI features.
Crypto tracking
Track cryptocurrency holdings with live prices in your net worth. Firefly III does not support crypto natively -- you would need manual tracking accounts.
Modern developer experience
TypeScript end-to-end, type-safe API client with Eden Treaty, Bun runtime for fast startup. If you are a TypeScript developer wanting to contribute, Trout's stack is more current. Firefly III is built with Laravel (PHP).
Frequently asked questions
What is the main difference between Trout and Firefly III?
The budgeting philosophy. Trout uses envelope budgeting (assign every dollar a job before you spend it). Firefly III uses double-entry bookkeeping (track every transaction as a debit and credit). Envelope budgeting is about planning spending. Double-entry is about recording it accurately.
Which is better for tracking expenses?
Firefly III is more thorough for pure expense tracking and accounting. It supports split transactions, piggy banks, recurring transactions, and detailed categorization. Trout focuses more on proactive budgeting -- knowing what you can spend before you spend it.
Can I switch from Firefly III to Trout?
There is no direct import tool. The two apps model financial data differently (double-entry vs envelope), so a straight migration is not practical. You would need to set up Trout from scratch with opening balances.
Which has a bigger community?
Firefly III, by a wide margin. It has 17,000+ GitHub stars, years of active development, and a large self-hosting community. Trout is a newer project with a growing community and fewer third-party integrations.
Try Trout
If envelope budgeting fits your style, start for free or self-host with Docker.