Best Practices

Request Efficiency

• Cache pricing results for 15–30 minutes for the same scenario rather than re-querying on every page load.
• Send only the fields you have — the API derives state, LTV, and other values automatically.
• Validate credit_score (300–850) and zipcode (5-digit string) client-side before the call.

Security

• Rotate your API key periodically and immediately upon suspected compromise.
• Never expose x-api-key in front-end JavaScript, mobile app binaries, or public repositories.
• All requests must be made over HTTPS.

LoanSifter Pricing

• All pricing_results in a single response come from one investor selected at par (100.00). The lender_name will be consistent across results.
• To change the investor selection price, pass productCharacteristics.desiredPrice (default: 100). Adjusting this shifts which investor is selected and therefore which rate stack is returned.
• For cross-investor comparisons at individual price points, make additional API calls with different parameters.

Affordability Programs

• Set first_time_homebuyer: true whenever the borrower qualifies — unlocks HomeReady and Home Possible tiers.
• Always pass monthly_income for conventional loans — the API evaluates AMI eligibility automatically.
• Surface program_name in your UI so borrowers can distinguish affordability products from standard pricing.

FHA-Specific

• FHA requires minimum 3.5% down for scores ≥ 580; 10% down for scores 500–579.
• Always surface mip_monthly — it materially affects total monthly payment.
• FHA MIP is permanent for 30-yr loans with LTV > 90%.

VA-Specific

• Set va_funding_fee_type accurately. Disabled veterans may be exempt — verify before submission.
• For VA IRRRL, always set cash_out: 0.

ARM-Specific

• Always disclose arm_caps and fully_indexed_rate to borrowers to satisfy TRID worst-case payment requirements.
• Explain the prepay_penalty terms on Non-QM ARM products before closing.
• Available arm_term values: "3", "5", "7", "10".

Non-QM / DSCR

• Always disclose prepay_penalty terms to borrowers before closing.
• If io_option: true, discuss long-term equity impact of the interest-only period.