mortgagemodeler 0.4.1

Flexible mortgage amortization and analytics tools in Python

MortgageModeler

Mortgage Modeler is a professional-grade mortgage modeling toolkit and CLI for simulating, analyzing, and comparing U.S. home loans — built for analysts, fintech engineers, and power users.

Overview

MortgageModeler provides in-depth mortgage analytics in Python, including:

• Amortization, payment, and payoff schedules
• Fixed, ARM, FHA, VA, USDA, and HELOC loan structures
• Recast and refinance logic with closing cost modeling
• Forward rate curve simulation and ARM caps/floors
• Effective APR and refinance breakeven point calculation
• CLI and API for scripting, exploration, or integration
• Composable modeling: combine ARM resets, forward rate paths, recast, refinance, and extra payments in one simulation

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Supported Features

• Flexible amortization modeling for fixed, ARM, FHA, VA, USDA, and HELOC loans
• Support for extra payments, lump sums, recasts, and refinance scenarios
• Forward rate simulation for ARMs with full cap/floor/margin logic
• Recast support based on lump-sum triggers or scheduled month
• Refinance modeling with rate/term changes and closing costs
• Effective APR calculation including points and fees
• Breakeven analysis to evaluate refinance timing
• CSV and JSON export of full amortization schedules
• Matplotlib-based amortization plotting
• Command-line interface (mortgagemodeler) and Python API

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Why MortgageModeler?

MortgageModeler was built for modern housing finance analysis — blending precision, flexibility, and transparency. Whether you're a fintech developer modeling loans, a homeowner exploring refinance timing, or a credit analyst stress-testing ARM resets, this library gives you full control and reproducibility — via Python or CLI.

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Supported loan types:

• fixed
• arm
• fha
• va
• usda
• heloc

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Installation

pip install mortgagemodeler

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Quickstart

Using the Python API:

from mortgagemodeler import Loan, LoanAmortizer

loan = Loan(principal=400000, rate=0.0625, term_months=360, origination_date="2023-01-01")
amortizer = LoanAmortizer(loan)
amortizer.plot()

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CLI Usage

Run amortization calculations and models via CLI:

mortgagemodeler amortize --balance 400000 --rate 6.25 --term 360 --type arm \
--index SOFR --margin 2.75 --arm-structure 5 6 --caps 2 1 5 --floors 0 0 0 \
--start-date 2023-01-01 --extra-payment 100 --show-apr --plot

Run complex scenarios including custom index, model curtailments and recast

mortgagemodeler amortize   --type arm   --balance 800000   --rate 5.25 \ 
--term 360   --margin 2.5   --arm-structure 3/1   --index-curve '{"2027-07-01": 4.0}' \
--index SOFR   --months 60   --curtailments 300000@42   --recast-month 45

Explore rich command line

Use --help to see all available options.

mortgagemodeler amortize --help

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Example Notebooks

Check github repowhich includes ready-to-run Jupyter examples in the examples/ folder:

• Fixed_vs_ARM.ipynb: Compare fixed vs adjustable-rate loan paths
• FHA_vs_Conventional.ipynb: Analyze MIP vs PMI cost impact
• Refinance_Breakeven.ipynb: Estimate the optimal time to refinance

Launch directly in Binder:

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License

MIT License © 2025 Arun Kumar