Build1 publisherNot yet confirmed elsewhere2 min readPublished
Contamos lets AI assistants edit the shared ledgers its users keep by hand
Contamos lets Claude, ChatGPT and other assistants create, edit and delete transactions in a shared multi-currency ledger through a remote MCP server. Nothing syncs from a bank, so the ledger is only as accurate as what members and their assistants enter.
The Engineer · Build desk
What happened
- An assistant acts with the permissions of the member who connected it, so its edits land in the same record every teammate sees.
- Contamos records assistant-made changes in an activity log, and that log is part of the paid Pro plan.
- The free plan includes AI access for one team with up to two members, three accounts and six months of history.
- Contamos says financial data an assistant reads goes to that AI provider under the provider's own terms and privacy policy.
- Era Context also links finance data to assistants over MCP, but describes bank-account aggregation as part of its service.
Compiled by The EngineerSomething wrong?How this is made
Why it matters
- exposure On the free plan, either of a team's two members can point an assistant at the shared ledger and delete entries, with no activity log afterwards showing what the assistant changed.
- decision Whichever assistant one member connects, its provider receives figures the whole team entered, so picking an assistant is a privacy decision for every member of the team.
- capability Couples and flatmates who split costs across currencies can query and update one shared record in plain language without linking a bank login to Contamos.
Two of Contamos's safeguards depend on the assistant behaving. The assistant is instructed to ask before it changes or deletes recorded data [7]. Contamos documents that as an instruction to the model. Its material does not describe a server-side check that refuses a delete without confirmation. An instruction is text the model reads, and how faithfully it is followed varies by model. Members can connect Claude, ChatGPT or any other compatible assistant [1], so one ledger can be edited by clients that behave differently.
The second safeguard is on the import path. When a member supplies a statement, Contamos says the assistant presents a dry run for review before it makes the entries [3]. A preview before a bulk write is the right design. It still relies on a person reading the preview, and an imported statement needs checking like any other entry [18].
The controls people hold directly are blunter. A member can disconnect an assistant from settings [6]. Pro, the plan with the activity log, is listed at $2.50 a month, billed annually at $29.99 [15]. Member roles are on the same Pro list [15]. The plan is sold by Qube SAS, which identifies itself in its privacy policy as established in Uruguay [10].
The currency handling is careful work. Each team keeps separate balances for euros, dollars, bitcoin and other enabled currencies [11]. According to Contamos, the ledger stores the exchange rate for the day a transaction occurred, so an old entry keeps its historical rate instead of silently picking up a newer one [12]. Anyone who has watched a spreadsheet restate last spring's dinner bill at today's rate will see why that matters. Accounts can hold several currencies side by side, and the product does not collapse them into one headline balance [13].
I think leaving out the bank feed is the right trade for this audience. Runtimewire's assessment is that the design favours groups that want a common record over a live, automatically synchronized view of each member's bank account [20].
What to watch
- Whether Contamos moves the activity log into the free plan or adds a server-side confirmation for assistant deletes.
- What early users report about assistant accuracy on statement imports after the Product Hunt launch Contamos has scheduled for October 24th, 2026.
- Whether Contamos adds bank aggregation like Era Context's; that would move responsibility for completeness back toward the vendor.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence45
- Adoption
- Insufficient
- Hype gap0
- Incentives
- Insufficient
- Confidence40
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Contamos connects to Claude, ChatGPT and other compatible assistants through a remote Model Context Protocol server.
- [2]
Once connected, an assistant can read balances and reports, answer questions in plain language, and create, edit or delete transactions.
- [3]
An assistant can import a statement supplied by the user; Contamos says the assistant presents a dry run for review before making those entries.
- [4]
Assistant actions follow the connected user's permissions; the assistant acts as the user, not as a separate read-only guest, and a change affects the record everyone on that team sees.
ReportedSupportedSource: Contamos assistant documentation, as reported by RuntimewireView cited source - [5]
Assistant-made changes appear in the activity log, which is a Pro feature.
- [7]
The assistant is instructed to ask before changing or deleting recorded data.
- [8]
Contamos says financial information read by an assistant goes to the provider of that AI service, under that provider's own terms and privacy policy.
- [9]
Contamos does not directly connect to bank accounts or automatically fetch transactions; users enter movements themselves or provide a statement for the assistant to process.
- [10]
Contamos is operated by Qube SAS, which identifies itself as established in Uruguay in its privacy policy.
- [11]
Contamos is designed for people who manage money together, such as a couple, household, flatmates or a shared project; each team records income, expenses and transfers in one ledger, with separate balances for euros, dollars, bitcoin and other enabled currencies.
- [12]
According to Contamos, the ledger stores the exchange rate for the day a transaction occurred, so later records retain that historical rate rather than silently reflecting a newer conversion.
- [13]
Accounts can contain multiple currencies side by side; the product avoids collapsing them into a single headline balance.
- [14]
The free plan includes one team, up to two members, three accounts and six months of history, and AI access is included.
- [15]
Contamos lists Pro at $2.50 per month, billed annually at $29.99, with unlimited teams, members, accounts and history, plus budgets, recurring transactions, member roles and activity logs.
- [16]
Contamos's homepage says its Product Hunt launch is scheduled for October 24th, 2026; the product page was already offering a free account as of October 7th.
- [17]
Era Context also connects finance data to AI assistants through MCP, while describing bank-account aggregation as part of its service.
- [18]
A missed entry remains missing; an imported statement still needs scrutiny.
- [19]
The approach avoids asking users to link bank credentials, but trades automatic updates for manual upkeep and review.
- [20]
Contamos's choices favor groups that want a common record over a live, automatically synchronized view of individual bank accounts.
- [21]
On the free plan, a team's assistant can create, edit or delete shared transactions, but the activity log that records assistant-made changes is not included.
Sources
1 independent publisher whose own reporting we read for this story.
- runtimewire.comContamos lets AI assistants write to a shared, multi-currency ledger
1 article · October 7, 2026
Topics and entities
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Topics
- Shared personal finance softwareFollow
- Model Context ProtocolFollow
- AI agent write accessFollow