{"openapi":"3.1.0","info":{"title":"Arca Savings Rates API","version":"1.0.2","description":"Read-only U.S. savings rates from Arca Savings: the APY on a $10,000 balance, what each rate requires, and when it last changed, plus inflation, the FDIC national average, Federal Reserve decisions and savings math. Rates are published only after each account's conditions are verified. Show `meta.attribution` with any answer that uses Arca's data. The examples in this document use fixed sample data from October 19, 2026: never quote them as current rates. Arca provides information, not financial advice.","contact":{"name":"Arca Savings","url":"https://arcasavings.com/developers"},"license":{"name":"Arca Savings Terms of Use","url":"https://arcasavings.com/terms"}},"servers":[{"url":"https://arcasavings.com/api/v1"}],"security":[{"ArcaKey":[]}],"paths":{"/summary":{"get":{"operationId":"getSummary","summary":"Highest savings rates, Federal Reserve decisions, inflation and the national average","description":"The highest savings APY Arca tracks, and the highest that asks nothing after opening (no direct deposit, linked checking account or minimum balance). Also the latest 12-month inflation rate (CPI), the FDIC national average savings rate, and recent Federal Reserve rate decisions. Use for \"best\", \"highest\" or \"top\" savings rate questions, \"is my rate beating inflation\", \"how does my rate compare to the national average\" and \"what did the Fed do\". Compare a rate with inflation as a spread in percentage points, not as a real return. Quote `sentence` as written.","responses":{"200":{"description":"Summary","content":{"application/json":{"schema":{"type":"object","required":["data","meta"],"additionalProperties":false,"properties":{"data":{"type":"object","required":["headline","inflation","fdic_national_average","fed_decisions"],"additionalProperties":false,"properties":{"headline":{"type":"object","required":["top","no_requirements","sentence"],"additionalProperties":false,"properties":{"top":{"$ref":"#/components/schemas/HeadlineFigure"},"no_requirements":{"oneOf":[{"$ref":"#/components/schemas/HeadlineFigure"},{"type":"null"}]},"sentence":{"type":"string","description":"Arca's one-sentence statement of both figures. Quote it as written."}}},"inflation":{"type":"object","required":["cpi_12mo_pct","period","label","source","arca_url"],"additionalProperties":false,"properties":{"cpi_12mo_pct":{"type":"number","description":"The 12-month change in consumer prices, percent. Compare with a savings rate as a spread in percentage points, not as a real return."},"period":{"type":"string","description":"The data month, YYYY-MM."},"label":{"type":"string","description":"How to name the period, e.g. \"12 months through September 2026\"."},"source":{"type":"string"},"arca_url":{"type":"string","description":"Arca's page comparing savings rates with inflation."}}},"fdic_national_average":{"type":"object","required":["apy","month"],"additionalProperties":false,"properties":{"apy":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"month":{"type":"string","description":"The month the FDIC published it for."}}},"fed_decisions":{"type":"array","items":{"type":"object","required":["date","action","size_pp","range","arca_url"],"additionalProperties":false,"properties":{"date":{"type":"string","format":"date"},"action":{"type":"string","enum":["raise","cut","hold"]},"size_pp":{"type":"number","description":"Size of the move in percentage points; 0 for a hold."},"range":{"type":"string","description":"The new federal funds target range."},"arca_url":{"type":"string","description":"Arca's article on this decision."}}}}}},"meta":{"$ref":"#/components/schemas/Meta"}}},"example":{"data":{"headline":{"top":{"apy":5,"accounts":[{"slug":"leader-bank","institution_name":"Leader Bank","product_name":"Zeugma Plus High Yield Savings","apy":5,"apy_without_requirements":2.5,"apy_after_promo":null,"requirements":"a linked checking account and direct deposit of $1,000+/mo","requirements_detail":null,"new_accounts_only":false,"rate_type":"promotional","promo_expires_at":"2027-03-31","last_change":null,"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-leader-bank"},{"slug":"axos","institution_name":"Axos Bank","product_name":"Axos ONE® Savings","apy":5,"apy_without_requirements":null,"apy_after_promo":1,"requirements":"a linked checking account and direct deposit of $1,000+/mo","requirements_detail":null,"new_accounts_only":false,"rate_type":"intro_then_variable","promo_expires_at":null,"last_change":null,"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-axos"}]},"no_requirements":{"apy":4.2,"accounts":[{"slug":"everbank","institution_name":"EverBank","product_name":"EverBank Performance Savings","apy":4.2,"apy_without_requirements":4.2,"apy_after_promo":null,"requirements":"","requirements_detail":null,"new_accounts_only":true,"rate_type":"variable","promo_expires_at":null,"last_change":null,"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-everbank"}]},"sentence":"As of October 19, 2026, the highest savings rate Arca tracks is 5.00% APY at Leader Bank Zeugma Plus High Yield Savings, tied with Axos ONE® Savings; both are promotional rates that require a linked checking account and direct deposit of $1,000+/mo. The highest savings rate with no requirements (no direct deposit, linked checking account or minimum balance) is 4.20% APY at EverBank Performance Savings, for new accounts only."},"inflation":{"cpi_12mo_pct":3.7,"period":"2026-09","label":"12 months through September 2026","source":"U.S. Bureau of Labor Statistics, Consumer Price Index (CPI-U)","arca_url":"https://arcasavings.com/blog/savings-rates-vs-inflation?utm_source=meta_ai&utm_medium=connector"},"fdic_national_average":{"apy":0.37,"month":"September 2026"},"fed_decisions":[{"date":"2026-09-16","action":"raise","size_pp":0.25,"range":"3.75%–4.00%","arca_url":"https://arcasavings.com/blog/fed-decision-savings-rates-september-2026?utm_source=meta_ai&utm_medium=connector"},{"date":"2026-07-29","action":"hold","size_pp":0,"range":"3.50%–3.75%","arca_url":"https://arcasavings.com/blog/fed-held-savings-rates-july-2026?utm_source=meta_ai&utm_medium=connector"}]},"meta":{"as_of":"2026-10-19","attribution":"Source: Arca Savings, rates as of October 19, 2026 (APY on a $10,000 balance). https://arcasavings.com/rates","disclaimer":"Arca provides information, not financial advice."}}}}},"401":{"description":"Missing or unknown API key","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"500":{"description":"Internal error. Every operation is safe to retry once.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}}}},"/accounts":{"get":{"operationId":"getAccounts","summary":"Current rates for named banks, or the top accounts","description":"Current savings rate for named banks or fintechs, what each rate requires, the rate without those requirements, and when each rate last changed. Pass `institution` with names or slugs (for example \"chase\", \"American Express\"), or `top` for the highest-rate accounts in Arca's ranking. Includes big-bank standard savings accounts such as Chase. Use for comparing named banks, \"what do I earn without direct deposit\", \"what does my bank pay\" and \"has my bank's rate changed\".","parameters":[{"name":"institution","in":"query","required":false,"description":"Comma-separated names or slugs, 1 to 10. Pass this or `top`, not both.","schema":{"type":"string"},"example":"ally,marcus,sofi"},{"name":"top","in":"query","required":false,"description":"The highest-rate accounts in Arca's ranking, 1 to 5. Pass this or `institution`, not both.","schema":{"type":"integer","minimum":1,"maximum":5}}],"responses":{"200":{"description":"Accounts","content":{"application/json":{"schema":{"type":"object","required":["data","meta"],"additionalProperties":false,"properties":{"data":{"type":"object","required":["accounts"],"additionalProperties":false,"properties":{"accounts":{"type":"array","items":{"$ref":"#/components/schemas/Account"}},"not_tracked":{"type":"array","items":{"type":"string","description":"A name from the request that matched no account Arca tracks."}}}},"meta":{"$ref":"#/components/schemas/Meta"}}},"example":{"data":{"accounts":[{"slug":"ally","institution_name":"Ally Bank","product_name":"Ally Online Savings","apy":3.1,"apy_without_requirements":3.1,"apy_after_promo":null,"requirements":"","requirements_detail":null,"new_accounts_only":false,"rate_type":"variable","promo_expires_at":null,"last_change":{"direction":"offer_ended","from":3.5,"to":3.1,"change_pp":-0.4,"detected_between":{"previous_capture":"2026-09-28","capture":"2026-10-05"}},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-ally"},{"slug":"marcus","institution_name":"Marcus (Goldman Sachs)","product_name":"Marcus Online Savings Account","apy":3.5,"apy_without_requirements":3.5,"apy_after_promo":null,"requirements":"","requirements_detail":null,"new_accounts_only":false,"rate_type":"variable","promo_expires_at":null,"last_change":{"direction":"up","from":3.4,"to":3.5,"change_pp":0.1,"detected_between":{"previous_capture":"2026-10-05","capture":"2026-10-12"}},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-marcus"},{"slug":"sofi","institution_name":"SoFi","product_name":"SoFi High-Yield Savings","apy":4.2,"apy_without_requirements":null,"apy_after_promo":3.3,"requirements":"direct deposit","requirements_detail":"Recurring direct deposit, or $5,000 in qualifying deposits every 31 days.","new_accounts_only":false,"rate_type":"intro_then_variable","promo_expires_at":"2026-12-31","last_change":{"direction":"up","from":4,"to":4.2,"change_pp":0.2,"detected_between":{"previous_capture":"2026-09-14","capture":"2026-09-21"}},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-sofi"}],"not_tracked":[]},"meta":{"as_of":"2026-10-19","attribution":"Source: Arca Savings, rates as of October 19, 2026 (APY on a $10,000 balance). https://arcasavings.com/rates","disclaimer":"Arca provides information, not financial advice."}}}}},"400":{"description":"Invalid parameters","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"401":{"description":"Missing or unknown API key","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"500":{"description":"Internal error. Every operation is safe to retry once.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}}}},"/rate-changes":{"get":{"operationId":"getRateChanges","summary":"Savings rate changes Arca detected in a date range","description":"Every savings rate change Arca detected in its weekly checks between two dates, newest first, with direction and size in percentage points. Arca checks on a schedule, so each change carries the window it was detected in, not an exact day. Filter by `institution` for one bank's record. A promotional rate that ended is reported as `offer_ended`, not as a cut. Use for \"who raised or cut rates\", \"did rates move after the Fed\" and \"how has X's rate changed\". Returns at most 25 changes.","parameters":[{"name":"since","in":"query","required":true,"description":"Start date, YYYY-MM-DD. Arca's record begins in May 2026.","schema":{"type":"string","format":"date"}},{"name":"until","in":"query","required":false,"description":"End date, YYYY-MM-DD. Defaults to the latest check.","schema":{"type":"string","format":"date"}},{"name":"institution","in":"query","required":false,"description":"Comma-separated names or slugs, 1 to 10.","schema":{"type":"string"},"example":"ally,marcus,sofi"}],"responses":{"200":{"description":"Rate changes, newest first","content":{"application/json":{"schema":{"type":"object","required":["data","meta"],"additionalProperties":false,"properties":{"data":{"type":"object","required":["history_starts","changes","truncated","arca_url"],"additionalProperties":false,"properties":{"history_starts":{"type":["string","null"],"format":"date","description":"The first weekly check in Arca's record for the institutions asked about."},"changes":{"type":"array","items":{"$ref":"#/components/schemas/Change"}},"truncated":{"type":"boolean","description":"True when more than 25 changes matched and only the newest 25 are returned. Narrow the dates or name institutions for the rest."},"arca_url":{"type":"string","description":"Arca's page of banks that raised or cut savings rates."},"not_tracked":{"type":"array","items":{"type":"string"}}}},"meta":{"$ref":"#/components/schemas/Meta"}}},"example":{"data":{"history_starts":"2026-05-18","changes":[{"slug":"marcus","institution_name":"Marcus (Goldman Sachs)","product_name":"Marcus (Goldman Sachs) Savings","direction":"up","from":3.4,"to":3.5,"change_pp":0.1,"detected_between":{"previous_capture":"2026-10-05","capture":"2026-10-12"},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-marcus"},{"slug":"ally","institution_name":"Ally Bank","product_name":"Ally Bank Savings","direction":"offer_ended","from":3.5,"to":3.1,"change_pp":-0.4,"detected_between":{"previous_capture":"2026-09-28","capture":"2026-10-05"},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-ally"},{"slug":"sofi","institution_name":"SoFi","product_name":"SoFi Savings","direction":"up","from":4,"to":4.2,"change_pp":0.2,"detected_between":{"previous_capture":"2026-09-14","capture":"2026-09-21"},"arca_url":"https://arcasavings.com/rates?utm_source=meta_ai&utm_medium=connector#rate-row-sofi"}],"truncated":false,"arca_url":"https://arcasavings.com/blog/savings-rate-changes?utm_source=meta_ai&utm_medium=connector"},"meta":{"as_of":"2026-10-19","attribution":"Source: Arca Savings, rates as of October 19, 2026 (APY on a $10,000 balance). https://arcasavings.com/rates","disclaimer":"Arca provides information, not financial advice."}}}}},"400":{"description":"Invalid parameters","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"401":{"description":"Missing or unknown API key","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"500":{"description":"Internal error. Every operation is safe to retry once.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}}}},"/calculate/interest":{"post":{"operationId":"calculateInterest","summary":"Interest earned at one or more APYs","description":"Interest a balance earns over a number of months at each APY given, and each result's difference from the first APY. Put the user's current rate first to answer \"how much more would I earn\". Rates are percent (4.2 = 4.20% APY). Use this for any dollar amount of interest, including the yearly difference between two rates on a balance. Inputs are not stored or logged.","requestBody":{"required":true,"content":{"application/json":{"schema":{"type":"object","required":["balance","apys"],"properties":{"balance":{"type":"number","minimum":0,"maximum":10000000},"months":{"type":"integer","minimum":1,"maximum":600,"default":12},"apys":{"type":"array","minItems":1,"maxItems":6,"items":{"type":"number","minimum":0,"maximum":25,"description":"Percent (4.2 = 4.20% APY)."}}}},"example":{"balance":15000,"apys":[0.01,4.2,5]}}}},"responses":{"200":{"description":"Interest","content":{"application/json":{"schema":{"type":"object","required":["data","meta"],"additionalProperties":false,"properties":{"data":{"type":"object","required":["results","formula","assumptions"],"additionalProperties":false,"properties":{"results":{"type":"array","items":{"type":"object","required":["apy","interest","difference_from_first"],"additionalProperties":false,"properties":{"apy":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"interest":{"type":"number","description":"Dollars."},"difference_from_first":{"type":"number","description":"Dollars, compared with the first APY."}}}},"formula":{"type":"string"},"assumptions":{"type":"array","items":{"type":"string"}}}},"meta":{"$ref":"#/components/schemas/Meta"}}},"example":{"data":{"results":[{"apy":0.01,"interest":1.5,"difference_from_first":0},{"apy":4.2,"interest":630,"difference_from_first":628.5},{"apy":5,"interest":750,"difference_from_first":748.5}],"formula":"interest = balance × ((1 + APY/100)^(months/12) − 1)","assumptions":["APY held constant for the period","Before taxes"]},"meta":{"as_of":"2026-10-19","attribution":"Source: Arca Savings, rates as of October 19, 2026 (APY on a $10,000 balance). https://arcasavings.com/rates","disclaimer":"Arca provides information, not financial advice."}}}}},"400":{"description":"Invalid parameters","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"401":{"description":"Missing or unknown API key","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"500":{"description":"Internal error. Every operation is safe to retry once.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}}}},"/calculate/goal":{"post":{"operationId":"calculateGoal","summary":"Monthly deposit needed to reach a savings goal","description":"The monthly deposit that reaches a savings goal in a number of months at a given APY, with deposits at the end of each month. Rates are percent (4.2 = 4.20% APY). Inputs are not stored or logged.","requestBody":{"required":true,"content":{"application/json":{"schema":{"type":"object","required":["goal_amount","months","apy"],"properties":{"goal_amount":{"type":"number","minimum":0,"maximum":10000000},"months":{"type":"integer","minimum":1,"maximum":600},"apy":{"type":"number","minimum":0,"maximum":25,"description":"Percent (4.2 = 4.20% APY)."},"starting_balance":{"type":"number","minimum":0,"maximum":10000000,"default":0}}},"example":{"goal_amount":10000,"months":18,"apy":4.2}}}},"responses":{"200":{"description":"Goal","content":{"application/json":{"schema":{"type":"object","required":["data","meta"],"additionalProperties":false,"properties":{"data":{"type":"object","required":["monthly_deposit","total_deposited","interest_earned","deposits_without_interest","formula","assumptions"],"additionalProperties":false,"properties":{"monthly_deposit":{"type":"number","description":"Dollars."},"total_deposited":{"type":"number","description":"Dollars."},"interest_earned":{"type":"number","description":"Dollars."},"deposits_without_interest":{"type":"number","description":"Dollars a month with no interest."},"formula":{"type":"string"},"assumptions":{"type":"array","items":{"type":"string"}}}},"meta":{"$ref":"#/components/schemas/Meta"}}},"example":{"data":{"monthly_deposit":539.51,"total_deposited":9711.18,"interest_earned":288.82,"deposits_without_interest":555.56,"formula":"r = (1 + APY/100)^(1/12) − 1; deposit = (goal − start × (1 + r)^n) × r / ((1 + r)^n − 1)","assumptions":["APY held constant","Deposits at the end of each month","Before taxes"]},"meta":{"as_of":"2026-10-19","attribution":"Source: Arca Savings, rates as of October 19, 2026 (APY on a $10,000 balance). https://arcasavings.com/rates","disclaimer":"Arca provides information, not financial advice."}}}}},"400":{"description":"Invalid parameters","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"401":{"description":"Missing or unknown API key","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"500":{"description":"Internal error. Every operation is safe to retry once.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}}}}},"components":{"securitySchemes":{"ArcaKey":{"type":"apiKey","in":"header","name":"X-Arca-Key"}},"schemas":{"Meta":{"type":"object","required":["as_of","attribution","disclaimer"],"additionalProperties":false,"properties":{"as_of":{"type":"string","format":"date","description":"The date the rates were last checked."},"attribution":{"type":"string","description":"Show this line with any answer that uses Arca's data."},"disclaimer":{"type":"string","description":"Show this with the answer."}}},"LastChange":{"type":"object","required":["direction","from","to","change_pp","detected_between"],"additionalProperties":false,"properties":{"direction":{"type":"string","enum":["up","down","offer_ended"],"description":"`offer_ended` means a promotional rate ended. It is not a rate cut."},"from":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"to":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"change_pp":{"type":"number","description":"The change in percentage points; negative when the rate fell."},"detected_between":{"type":"object","required":["previous_capture","capture"],"additionalProperties":false,"properties":{"previous_capture":{"type":"string","format":"date","description":"The last weekly check that showed the old rate."},"capture":{"type":"string","format":"date","description":"The first weekly check that showed the new rate."}},"description":"Arca checks rates weekly, so a change is known to have happened between these two checks, not on an exact day."}}},"Change":{"type":"object","required":["slug","institution_name","product_name","direction","from","to","change_pp","detected_between","arca_url"],"additionalProperties":false,"properties":{"slug":{"type":"string"},"institution_name":{"type":"string"},"product_name":{"type":"string"},"direction":{"type":"string","enum":["up","down","offer_ended"],"description":"`offer_ended` means a promotional rate ended. It is not a rate cut."},"from":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"to":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"change_pp":{"type":"number","description":"The change in percentage points; negative when the rate fell."},"detected_between":{"type":"object","required":["previous_capture","capture"],"additionalProperties":false,"properties":{"previous_capture":{"type":"string","format":"date","description":"The last weekly check that showed the old rate."},"capture":{"type":"string","format":"date","description":"The first weekly check that showed the new rate."}},"description":"Arca checks rates weekly, so a change is known to have happened between these two checks, not on an exact day."},"arca_url":{"type":"string","description":"This account on Arca Savings."}}},"Account":{"type":"object","required":["slug","institution_name","product_name","apy","apy_without_requirements","apy_after_promo","requirements","requirements_detail","new_accounts_only","rate_type","promo_expires_at","last_change","arca_url"],"additionalProperties":false,"properties":{"slug":{"type":"string"},"institution_name":{"type":"string"},"product_name":{"type":"string"},"apy":{"type":"number","description":"Percent. For high-yield accounts, the rate when requirements are met. For big banks, the standard savings rate."},"apy_without_requirements":{"type":["number","null"],"description":"Percent. The rate without meeting the requirements. Equal to `apy` when there are none. Null when not recorded."},"apy_after_promo":{"type":["number","null"],"description":"Percent. The rate after the promotional period ends, for rates that revert. Its requirements still apply. Null otherwise."},"requirements":{"type":"string","description":"What the rate requires, in Arca's words. Empty when nothing is required."},"requirements_detail":{"type":["string","null"],"description":"Arca's longer description of the requirements, when Arca has written one."},"new_accounts_only":{"type":"boolean","description":"True when the rate is only for new accounts or customers. Not a requirement."},"rate_type":{"type":"string","enum":["variable","promotional","intro_then_variable"]},"promo_expires_at":{"type":["string","null"],"format":"date","description":"When a promotional rate ends, when known."},"last_change":{"oneOf":[{"$ref":"#/components/schemas/LastChange"},{"type":"null"}]},"arca_url":{"type":"string","description":"This account's page on Arca Savings, with its full terms and a link to the bank's own site."}}},"HeadlineFigure":{"type":"object","required":["apy","accounts"],"additionalProperties":false,"properties":{"apy":{"type":"number","description":"Percent (4.2 = 4.20% APY)."},"accounts":{"type":"array","items":{"$ref":"#/components/schemas/Account"}}}},"Error":{"type":"object","required":["error"],"additionalProperties":false,"properties":{"error":{"type":"object","required":["code","message"],"additionalProperties":false,"properties":{"code":{"type":"string","enum":["bad_request","unauthorized","internal"]},"message":{"type":"string"}}}}}}}}