spacious-team/investbook

Description and use

**Summary**
spacious‑team / investbook is an open‑source Java library that calculates the net performance of investments and trading activities, taking into account commissions, taxes (both withheld and expected), dividends, and coupon payments. With 323 ★ and 105 forks, it is actively maintained (last update 2026‑06‑29) and positioned as a fast‑track solution for integrating monetisation, billing, or PSP (payment‑service‑provider) flows into financial applications.

**Value**
Investbook abstracts the complex math behind total‑return‑of‑investment (including fees, tax regimes, and cash‑flow events) into reusable APIs, enabling product teams to embed accurate profitability metrics directly into dashboards, risk engines, or checkout experiences without reinventing the logic. This reduces development effort, improves financial reporting fidelity, and supports compliance by automatically handling tax‑deduction scenarios.

**Practical adoption path**

1. **Proof‑of‑concept** – Clone the repo, run the provided unit‑tests, and use the sample README snippets to evaluate a single asset class (e.g., equities with dividend handling).
2. **Integration** – Add the Maven/Gradle dependency to your service, replace the demo data with your own transaction and tax tables, and expose a thin wrapper (REST or gRPC) for your billing/checkout module.
3. **Pilot** – Deploy the wrapper in a staging environment, run end‑to‑end tests against real payment‑service‑provider (PSP) callbacks, and verify the calculated net returns against a manual spreadsheet.
4. **Scale** – Extend the model to cover additional instruments (bonds, derivatives) and automate periodic runs as part of your payment‑operations pipeline.

**Production readiness**
The project scores high on production readiness: recent commits, a healthy star/fork count, and a broad set of topics indicate an active community and sufficient documentation for a serious pilot. While no critical metadata risks were identified, a final review of the license (MIT‑style) and a security audit of its dependencies is recommended before full‑scale deployment. Once those checks are complete, Investbook can be considered production‑grade for integrating billing, checkout, or PSP‑related financial calculations.

Use in a workflow

spacious-team/investbook helps integrate monetization, billing, or PSP flows faster.

• integrate billing or checkout
• evaluate PSP flows
• automate payment operations

Limitations and review notes

High for an OSS candidate: recent activity, adoption, and ecosystem signals are strong enough for a serious pilot.