{"educationOnly":true,"disclaimer":"Educational calculator only. Not an offer, pre-approval, or lender directory.","endpoint":"https://trybitstack.com/api/tools/down-payment","path":"/api/tools/down-payment","methods":{"GET":"No tool param: this discovery document + JSON schemas. With tool + inputs: execute.","POST":"JSON body with tool (or name) plus the tool input fields.","OPTIONS":"CORS preflight."},"sameAs":{"interactive":"https://trybitstack.com/tools/down-payment-calculator","markdown":"https://trybitstack.com/api/tools/down-payment-calculator.md","webmcp":"Chrome WebMCP tools of the same names on the interactive page (document.modelContext.registerTool). No-op without navigator/document.modelContext."},"tools":[{"name":"run_down_payment","title":"Run down-payment comparison","description":"Run the educational sell vs pledge vs cash-out Bitcoin down-payment comparison for a home price, down payment, and BTC spot. Optional dump stress (0/30/50/80), illustrative tax rate, and cash-out origination LTV match the on-page calculator. Returns the same numbers the UI computes. Not an application.","inputSchema":{"type":"object","description":"Inputs already used by the on-page calculator. Down payment is a USD amount or percent of home price; BTC sold/pledged is derived (this model does not take a holdings inventory).","properties":{"homePriceUsd":{"type":"number","description":"Home purchase price in USD."},"downPaymentValue":{"type":"number","description":"Down payment as USD (downPaymentMode=usd) or percent of home price (downPaymentMode=percent)."},"downPaymentMode":{"type":"string","enum":["usd","percent"],"description":"How to interpret downPaymentValue. Defaults to usd.","default":"usd"},"btcSpotPrice":{"type":"number","description":"BTC spot price in USD used at origination."},"dumpPercent":{"type":"number","enum":[0,30,50,80],"description":"Post-origination BTC dump stress in percent. Defaults to 0 (spot).","default":0},"taxRatePercent":{"type":"number","description":"Illustrative tax rate used to gross up a sale. Default 0. Not tax advice.","default":0,"minimum":0,"maximum":99.99},"cashOutOriginationLtv":{"type":"number","description":"Cash-out origination LTV percent. Default 50. Typical range 35–50.","default":50,"minimum":1,"maximum":99}},"required":["homePriceUsd","downPaymentValue","btcSpotPrice"]},"outputSchema":{"type":"object","properties":{"educationOnly":{"type":"boolean","const":true},"disclaimer":{"type":"string"},"comparison":{"type":"object","properties":{"isValid":{"type":"boolean"},"downPaymentUsd":{"type":"number","description":"Resolved down payment in USD."},"downPaymentPercentOfHome":{"type":"number","description":"Down payment as a percent of home price."},"spotPrice":{"type":"number","description":"BTC spot used at origination."},"stressedPrice":{"type":"number","description":"BTC price after the dump stress."},"dumpPercent":{"type":"number","enum":[0,30,50,80]},"taxRatePercent":{"type":"number","description":"Illustrative tax rate applied to the sell path."},"taxIsIllustrative":{"type":"boolean","const":true},"sell":{"type":"object","properties":{"btcSoldAtSpot":{"type":"number","description":"BTC sold at spot to raise the down payment."},"grossUsdSoldAtSpot":{"type":"number","description":"Gross USD sale including illustrative tax gross-up."},"taxUsd":{"type":"number","description":"Illustrative tax dollars."},"netUsd":{"type":"number","description":"Net USD equal to the down payment."},"usdValueOfSoldBtcAtStress":{"type":"number","description":"USD value of the sold BTC after the dump."},"btcNeededIfSoldAtStressedPrice":{"type":"number","description":"BTC that would be sold if selling after the dump."},"extraBtcIfSoldAfterDump":{"type":"number","description":"Extra BTC needed if selling after the dump vs at spot."}}},"pledge":{"type":"object","description":"Better/Coinbase-style published example — not an application.","properties":{"creditLineUsd":{"type":"number","description":"Credit line equal to the down payment."},"collateralUsdAtOrigination":{"type":"number","description":"Collateral USD at 250% collateralization."},"btcPledged":{"type":"number","description":"BTC pledged at origination."},"collateralUsdAtStress":{"type":"number","description":"Collateral marked at the stressed price."},"impliedLtvAtStress":{"type":"number","description":"Implied credit/collateral percent after the dump."},"dumpChangesTerms":{"type":"boolean","const":false},"dumpTriggersLiquidation":{"type":"boolean","const":false},"liquidationOnlyAfterDelinquencyDays":{"type":"number"},"ratePremium":{"type":"string"},"ficoFloor":{"type":"number"},"sourceLabel":{"type":"string"}}},"cashOut":{"type":"object","properties":{"loanAmountUsd":{"type":"number","description":"Cash-out loan amount (the down payment)."},"originationLtv":{"type":"number","description":"Origination LTV percent used for this path."},"collateralUsdAtOrigination":{"type":"number","description":"Collateral USD required at origination."},"btcPledged":{"type":"number","description":"BTC pledged as cash-out collateral."},"currentLtv":{"type":"number","description":"LTV at the stressed BTC price."},"liquidationPrice":{"type":"number","description":"BTC price that hits the liquidation threshold."},"marginCallPrice":{"type":"number","description":"BTC price that hits the margin-call threshold."},"dumpStatus":{"type":"string","enum":["healthy","margin","liquidated"],"description":"Loan health at the stressed price (same mapping as the UI)."},"dumpTriggersLiquidation":{"type":"boolean"}},"required":["loanAmountUsd","originationLtv","collateralUsdAtOrigination","btcPledged","currentLtv","liquidationPrice","marginCallPrice","dumpStatus","dumpTriggersLiquidation"]}},"required":["isValid","downPaymentUsd","sell","pledge","cashOut"]}},"required":["educationOnly","disclaimer","comparison"]}},{"name":"compare_ltv_buckets","title":"Compare cash-out LTV buckets","description":"Compare the cash-out Bitcoin loan path at origination LTV buckets (30%, 35%, and 50%). 30% is the round origination that stays healthy after a 50% dump (scenario, not a forecast); 35% and 50% are the typical cash-out range. Same loan LTV / margin-call / liquidation math as the on-page calculator. Savings-bucket BTC only. Education only — not an application.","inputSchema":{"type":"object","description":"Same inputs as run_down_payment except origination LTV, which is compared at 30%, 35%, and 50%.","properties":{"homePriceUsd":{"type":"number","description":"Home purchase price in USD."},"downPaymentValue":{"type":"number","description":"Down payment as USD (downPaymentMode=usd) or percent of home price (downPaymentMode=percent)."},"downPaymentMode":{"type":"string","enum":["usd","percent"],"description":"How to interpret downPaymentValue. Defaults to usd.","default":"usd"},"btcSpotPrice":{"type":"number","description":"BTC spot price in USD used at origination."},"dumpPercent":{"type":"number","enum":[0,30,50,80],"description":"Post-origination BTC dump stress in percent. Defaults to 50 for this comparison (0/30/50/80 still valid). The 50% dump is a scenario toggle, not a forecast.","default":50},"taxRatePercent":{"type":"number","description":"Illustrative tax rate used to gross up a sale. Default 0. Not tax advice.","default":0,"minimum":0,"maximum":99.99}},"required":["homePriceUsd","downPaymentValue","btcSpotPrice"]},"outputSchema":{"type":"object","properties":{"educationOnly":{"type":"boolean","const":true},"disclaimer":{"type":"string"},"dumpPercent":{"type":"number","enum":[0,30,50,80],"description":"Dump stress applied after origination (same chips as the page)."},"originationLtvs":{"type":"array","items":{"type":"number"},"description":"Origination LTV percents compared (30%, 35%, and 50%)."},"maxHealthyOriginationLtvAtDump":{"type":"number","description":"Origination LTV whose stressed LTV equals the 65% margin-call line after this dump. At a 50% dump this is 32.5%; origination strictly below it stays healthy. 30% is the round healthy bucket."},"buckets":{"type":"array","items":{"type":"object","properties":{"originationLtv":{"type":"number","description":"Origination LTV percent for this bucket."},"isValid":{"type":"boolean"},"downPaymentUsd":{"type":"number","description":"Resolved down payment in USD."},"cashOut":{"type":"object","properties":{"loanAmountUsd":{"type":"number","description":"Cash-out loan amount (the down payment)."},"originationLtv":{"type":"number","description":"Origination LTV percent used for this path."},"collateralUsdAtOrigination":{"type":"number","description":"Collateral USD required at origination."},"btcPledged":{"type":"number","description":"BTC pledged as cash-out collateral."},"currentLtv":{"type":"number","description":"LTV at the stressed BTC price."},"liquidationPrice":{"type":"number","description":"BTC price that hits the liquidation threshold."},"marginCallPrice":{"type":"number","description":"BTC price that hits the margin-call threshold."},"dumpStatus":{"type":"string","enum":["healthy","margin","liquidated"],"description":"Loan health at the stressed price (same mapping as the UI)."},"dumpTriggersLiquidation":{"type":"boolean"}},"required":["loanAmountUsd","originationLtv","collateralUsdAtOrigination","btcPledged","currentLtv","liquidationPrice","marginCallPrice","dumpStatus","dumpTriggersLiquidation"]}},"required":["originationLtv","isValid","downPaymentUsd","cashOut"]}}},"required":["educationOnly","disclaimer","dumpPercent","originationLtvs","maxHealthyOriginationLtvAtDump","buckets"]}}],"citations":[{"id":"ltv-rule","heading":"What is the LTV rule, and why it matters","url":"https://trybitstack.com/tools/ltv-calculator","lead":"Loan-to-value (LTV) is the loan divided by Bitcoin collateral, as a percent. The LTV rule: originate low enough that a large BTC drop still sits below the lender’s margin-call line. Lower LTV means more buffer; higher LTV means more liquidation risk. BitStack is not a lender."},{"id":"dont-sell","heading":"Who this down-payment model is for (don’t sell the stack)","url":"https://trybitstack.com/tools/down-payment-calculator","lead":"This calculator is for Bitcoiners who already hold BTC and need dollars for a house — not for people shopping lenders. Selling coins for a down payment is a last resort in this model: the stack is gone and cannot be rebought at the sale price. BitStack is not a lender. Education only."},{"id":"mortgage-math","heading":"Crypto-backed mortgage math, in plain language","url":"https://trybitstack.com/tools/down-payment-calculator","lead":"A crypto-backed mortgage down payment means you post Bitcoin as collateral and receive dollars without selling the coins. Cash-out math is LTV: dollars borrowed divided by BTC value. Pledge-style math posts more collateral than the credit (for example 250% collateral / 40% credit). BitStack models both as education, not a loan offer. BitStack is not a lender."},{"id":"four-buckets","heading":"What are BitStack’s four buckets?","url":"https://trybitstack.com/learn/bitstack-framework","lead":"BitStack organizes a Bitcoin-native portfolio into four buckets: Savings (self-custodied BTC), Investments (MSTR, miners), Income (yield without selling BTC), and Other (legacy assets not yet converted). The framework answers why you own each asset — it is not a single recommended mix. Only Savings-bucket BTC is pledgeable collateral in the calculators."},{"id":"calculator-howto","heading":"How to run this calculator (humans and agents)","url":"https://trybitstack.com/tools/down-payment-calculator","lead":"Humans type home price and down payment, then read sell vs pledge vs cash-out and the 30/35/50% origination buckets. Agents call POST or GET /api/tools/down-payment with tool=run_down_payment or compare_ltv_buckets, or fetch /.well-known/mcp.json. Chrome WebMCP registers the same tools when document.modelContext exists. Education only. BitStack is not a lender."},{"id":"credit-ready","heading":"Sell for the down payment vs pledge with a liquidity buffer","url":"https://trybitstack.com/tools/down-payment-calculator","lead":"Selling Bitcoin for a down payment raises cash and can look conventional on a mortgage file, but the stack is sold. Pledging BTC keeps coins as collateral; staying credit-ready then means a separate cash or BTC buffer so a dump does not force a margin call. Planning contrast only. BitStack is not a lender."}],"examples":{"run_down_payment":{"tool":"run_down_payment","homePriceUsd":500000,"downPaymentValue":100000,"downPaymentMode":"usd","btcSpotPrice":100000,"dumpPercent":0},"compare_ltv_buckets":{"tool":"compare_ltv_buckets","homePriceUsd":500000,"downPaymentValue":100000,"downPaymentMode":"usd","btcSpotPrice":100000,"dumpPercent":0},"curl":"curl -sS -X POST https://trybitstack.com/api/tools/down-payment -H 'Content-Type: application/json' -d '{\"tool\":\"run_down_payment\",\"homePriceUsd\":500000,\"downPaymentValue\":100000,\"btcSpotPrice\":100000}'","get":"https://trybitstack.com/api/tools/down-payment?tool=run_down_payment&homePriceUsd=500000&downPaymentValue=100000&btcSpotPrice=100000"}}