Accounting · head to head
Causal vs Firefly III
Causal
Accounting
Formula-based financial planning and modelling, now sold as Lucanet xP&A
- From
- On request
- Rated
- -
Firefly III
Personal Finance
Free, open source, self-hosted personal finance manager with double-entry style accounting
- From
- Free
- Rated
- -
The short version
- Only Firefly III has a free tier, so it costs nothing to try first.
- Each has a real cost: Causal causal was acquired by Lucanet on 31 October 2024 and the independent brand has been retired in favour of Lucanet xP&A, so the roadmap, support and pricing you buy are Lucanet’s and not the ones the product built its reputation on.; Firefly III there is no official managed hosting, so a non-technical user has no easy on-ramp the way Actual Budget offers with its paid hosted sync.
- They diverge on capability: Causal covers Variable-based modelling, Firefly III covers Double-entry style ledger.
- Prices and features above were last checked on 1 September 2026.
Where they differ
Only the attributes on which Causal and Firefly III actually diverge.
| Attribute | Causal | Firefly III |
|---|---|---|
| Starting price | On request | Free |
| Pricing model | quote | Open source, no licence fee |
| Free tier | No | Yes |
| Platforms | Web | Web, Linux, Docker |
| Category | Accounting | Personal Finance |
Identical on both: user rating (Not yet rated).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Causal
- Variable-based modelling
- Dimensional breakdowns
- Scenario and range inputs
- Actuals integration
- Interactive dashboards
- Version history
- Spreadsheet import
- Workforce and headcount planning
Only in Firefly III
- Double-entry style ledger
- Multi-currency accounts
- Bill and subscription tracking
- Rule engine
- Reports and charts
- API access
What people use each for
The jobs each tool is most often brought in to do.
Causal
- A finance team whose three-statement Excel model has become too fragile to change safely before every board meetingnot Firefly III
- A company that needs to show a range of outcomes rather than a single forecast, with uncertainty modelled directly in the driversnot Firefly III
- A budget owner outside finance who should adjust hiring or spend assumptions and see the effect without being given edit access to the master spreadsheetnot Firefly III
- A group already running Lucanet for consolidation and reporting that wants planning on the same platform rather than a separate toolnot Firefly III
Firefly III
- A self-hoster already running a home server or NAS who wants their financial ledger on the same infrastructurenot Causal
- Someone who wants double-entry style accuracy rather than simple envelope budgetingnot Causal
- A privacy-focused user who refuses to put financial data on any third-party server, hosted or otherwisenot Causal
- A developer who wants API access to build custom bank import scripts for accounts with no standard connectornot Causal
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Causal
- Causal was acquired by Lucanet on 31 October 2024 and the independent brand has been retired in favour of Lucanet xP&A, so the roadmap, support and pricing you buy are Lucanet’s and not the ones the product built its reputation on.
- Self-serve pricing is gone: the old causal.app pricing page now redirects to a Lucanet solution page, so what was a transparent product you could sign up for is an enterprise sales conversation with no published rate.
- The variable-based model is a genuine departure from spreadsheet thinking, so an accountant fluent in Excel must relearn how to express a model, and the team members who could previously all edit the forecast often cannot at first.
- Deep Excel compatibility is limited by design; complex existing workbooks with macros, circular references or heavy lookups do not import cleanly and have to be rebuilt, which turns a tool evaluation into a modelling project.
- Consolidation, statutory reporting and multi-entity currency handling are weaker than in dedicated corporate performance management suites, so a group with several legal entities usually needs Lucanet’s other modules alongside it, raising the real cost well past the planning tool alone.
Firefly III
- There is no official managed hosting, so a non-technical user has no easy on-ramp the way Actual Budget offers with its paid hosted sync.
- The double-entry-influenced model is less intuitive for newcomers than simple envelope budgeting, and the learning curve is real.
- Automatic bank sync depends on the community-run importer and third-party connectors, and coverage and reliability vary a lot by bank and country.
- Mobile access is via a web interface rather than a polished native app, which is a step behind Actual Budget or Lunch Money on phones.
- Because there is no company behind it, security patching and feature development depend entirely on volunteer maintainer time.
Pricing, plan by plan
Causal
On request- Lucanet xP&A (formerly Causal)$undefined/year
- Variable-based planning models with dimensions and scenarios
- Actuals integration from accounting, CRM and warehouse sources
- Interactive dashboards for non-finance stakeholders
Firefly III
Free- Firefly IIIFree
- Full functionality, self-hosted
- No usage limits
- Community support, donations accepted
Which should you pick?
Choose Causal if
- You need variable-based modelling.
- You also want dimensional breakdowns.
Choose Firefly III if
- You need double-entry style ledger.
- You want to start without paying.
- You work on Web, Linux, Docker.
- You also want multi-currency accounts.
Questions people ask
- Is Causal or Firefly III better?
- Neither clearly leads. Causal starts at On request and Firefly III at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Causal or Firefly III?
- Firefly III has a free tier; the other does not. Paid plans start at On request for Causal and Free for Firefly III.
- Does Causal or Firefly III run on more platforms?
- Causal runs on Web. Firefly III runs on Web, Linux, Docker.
- Can I use Firefly III for free?
- Yes. Firefly III has a free tier, so you can try it without paying. Causal starts at On request.
- What is Causal best used for?
- Causal is most often used for a finance team whose three-statement excel model has become too fragile to change safely before every board meeting, a company that needs to show a range of outcomes rather than a single forecast, with uncertainty modelled directly in the drivers, a budget owner outside finance who should adjust hiring or spend assumptions and see the effect without being given edit access to the master spreadsheet, a group already running lucanet for consolidation and reporting that wants planning on the same platform rather than a separate tool. Of those, a finance team whose three-statement excel model has become too fragile to change safely before every board meeting and a company that needs to show a range of outcomes rather than a single forecast, with uncertainty modelled directly in the drivers are not what Firefly III is typically brought in for.
- What can Causal do that Firefly III cannot?
- Causal covers Variable-based modelling, Dimensional breakdowns, Scenario and range inputs, Actuals integration. Firefly III covers Double-entry style ledger, Multi-currency accounts, Bill and subscription tracking, Rule engine.
Answered from the vendors’ own pages
Causal: Does Causal still exist?
The product does, as Lucanet xP&A. The independent Causal brand and self-serve offering have been retired following the October 2024 acquisition.
Firefly III: Can I pay someone to host Firefly III for me?
Not through the core project; some third-party providers sell Firefly III hosting independently, but there is no official managed service.
Causal: What does it cost now?
Nothing is published. The former pricing page redirects to Lucanet, and the product is quoted as part of the Lucanet CFO Solution Platform.
Firefly III: Does it support multiple currencies?
Yes, natively, including accounts and transactions in different currencies.
Causal: Can I import my existing Excel model?
Simple workbooks import. Models with macros, circular references or heavy lookup chains have to be rebuilt around named variables, which is the real migration cost.
Firefly III: Is it really free with no paid tier?
Yes, the software is free and open source under the AGPL; the project accepts donations but sells nothing.
Causal: Is it a replacement for a consolidation tool?
No. It plans and forecasts. Statutory consolidation and multi-entity reporting sit in Lucanet’s other modules.
Related pages
More on Firefly III
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