Split Cost

What Split Cost is for

"Split $340 three ways", "who actually owes whom after this trip?", "minimize the number of payments to settle up" — the arithmetic behind a group trip's shared costs, done properly instead of eyeballed.

What it does

equal_split, percentage_split and weighted_split divide a total among named people — evenly, by named percentages, or by an arbitrary weight (nights stayed, mileage driven, whatever fairness basis fits) — using a largest-remainder apportionment method so the shares always sum EXACTLY to the total, with no floating-point drift leaving a stray cent unaccounted for. itemized_split handles the more realistic case of a bill made of separate line items, each shared only by the people who actually had that item, and aggregates each person's total owed across all of them. expense_summary_by_person takes a raw list of expenses (who paid, how much, who it was shared with) and computes what everyone actually paid versus their equal share of everything they took part in. compute_balances nets explicit paid/owed totals into a single balance per person. settle_up is the heart of the connector: a real debt-simplification algorithm that takes those balances and works out the smallest practical set of direct payments to zero everyone out, instead of everyone paying everyone back for every individual expense — provably no more than (people with a nonzero balance − 1) payments, and matching the true minimum in the large majority of real cases. verify_balances sanity-checks that a set of balances actually nets to zero before you try to settle it. full_trip_settlement runs the whole pipeline — from a raw expense list straight through to a final list of who pays whom how much — in one call. splitcost_glossary defines the underlying terms.

What it is not

Not a payments product — it computes who owes what and suggests the settling transactions; it doesn't move any money or connect to any bank, card, or payment app. No currency is assumed anywhere: it computes in whatever units your numbers are already in. The debt-simplification algorithm is a well-known, widely used greedy heuristic (match the largest creditor against the largest debtor, repeat) rather than an exhaustive search for the mathematically smallest possible transaction count — for the vast majority of real group trips it produces the same result an exhaustive search would, but a handful of contrived balance combinations admit one fewer transaction through exact subset-sum matching, which this connector doesn't attempt.

Split Cost — Privacy Policy

Effective 26 September 2026. Unify Dynamics LLC ("we", "us"), Menlo Park, California.

What Split Cost is. Split Cost is a connector (an MCP server and REST API) that AI assistants and personal agents call on your behalf to run a pure-compute group-expense-splitting calculation. You interact with your assistant; the assistant sends us only the numbers needed for that one calculation.

What we receive. The arguments of each tool call — amounts, names, percentages, weights, or a list of expenses with who paid and who participated — the technical headers needed to serve the request (an IP address or a client identifier supplied by the assistant, and a Pro API key if you have one), and standard server logs. The "names" in a split are whatever labels you use (first names, initials, nicknames) — we have no way to know, and don't need to know, who they really are.

Everything is computed locally from the numbers you provide, and nothing is stored. There is no upstream call at all — this connector has no bundled dataset and no live lookups, it is pure arithmetic — and no request, including names, amounts, or the resulting splits and settlement transactions, is logged in request bodies, recorded, or used to train anything.

What we do not receive or store. We do not receive your conversation with the assistant, and we do not build a profile from your queries: each request is computed independently and nothing carries over between requests. Rate-limit counters (a client identifier and timestamps) are held in memory for at most 24 hours. Hosting-provider access logs, which contain IP addresses and request paths but not request bodies, are retained for up to 30 days for security and abuse prevention.

Sub-processors. None — every calculation runs locally with no dataset and no upstream call of any kind. Hosting: Vercel (United States regions).

Legal bases and your rights. Our processing is necessary to provide the service you request through your assistant. Because we store no personal data beyond short-lived logs, requests to access, correct or delete personal data are usually satisfied automatically; you can still contact agent@connectorbay.com and we will respond within 30 days. We do not sell or share personal information and do not use your data to train models.

Children. Split Cost is a general-audience service operated by the adult using the assistant.

Changes. We will post changes here with a new effective date.

Split Cost — Terms of Service

Effective 26 September 2026. These terms govern use of the Split Cost connector ("the Service") operated by Unify Dynamics LLC ("we", "us").

1. The Service. Split Cost is a pure-computation group-expense-splitting and debt-simplification calculator. It is accessed through an AI assistant or directly over MCP or HTTP, and performs no lookups and stores no data — every result comes directly from the numbers supplied in that request.
2. Not a payments service. The Service computes who owes what and suggests settling transactions; it does not move money, connect to any bank or card, or verify that any suggested payment actually happened. Acting on a result (e.g. actually paying someone) is entirely up to you.
3. Computational tool, not a guarantee of fairness. Splitting method (equal, percentage, weighted, itemized) and settle-up results reflect the inputs and method you chose; the Service has no way to verify that the amounts, participants, or names you provide are accurate or complete.
4. Acceptable use. Automated use within the published rate limits is welcome.
5. Availability. The Service is provided "as is" without warranty. We may change, limit or discontinue it at any time.
6. Data. Our Privacy Policy describes what we process. In short: every calculation is computed locally from the numbers you provide, and nothing is stored.
7. Pro keys. Optional Pro API keys are issued at our discretion, are personal to the holder and may be revoked for abuse.
8. Liability. To the fullest extent permitted by law, Unify Dynamics LLC is not liable for any loss or dispute arising from use of, or reliance on, the Service, including any disagreement among group members about a split or settlement computed here. Our total liability is limited to US $100.
9. Governing law. California law; venue in San Mateo County, California.
10. Contact. Unify Dynamics LLC · agent@connectorbay.com · https://connectorbay.com/splitcost

Split Cost support

Email agent@connectorbay.com. We answer within two business days.

• MCP endpoint: https://splitcost.connectorbay.com/mcp
• REST API: https://splitcost.connectorbay.com/openapi.json
• Live status: https://splitcost.connectorbay.com/health

When you report a problem, include the question you asked your agent, roughly when, and which agent you used (for example Claude, ChatGPT or Gemini). Never send us passwords, account numbers or ID numbers. Split Cost never asks for them.