Fixer for AI agents
Fixer is a currency data API providing real-time and historical exchange rates for 170 world currencies, used by finance and ecommerce applications that price across markets. Connect it once through Arc0, and your agent, or Claude, ChatGPT and Cursor, can use it through one MCP endpoint, limited to what each user approved.
What agents do in Fixer.
Check today's exchange rate
Get the latest exchange rate for a currency pair before converting an invoice amount.
Pull historical rates
Get historical rates for a date range to chart how a currency has moved.
Read-only rate lookups
Keep every exchange rate call read-only, since the API only reports rates and never converts funds.
3 Fixer actions, graded by risk.
Every Fixer action is tagged read, write or destructive, so one policy covers the whole app and new actions inherit the right default.
read
3Look things up. Allowed by default.
- fixer.get_latest_ratesGet Latest Exchange Rates
- fixer.get_historical_ratesGet Historical Rates
- fixer.get_supported_symbolsGet Supported Symbols
write
0Create and change things. Allow, or ask the user first.
- No write actions.
destructive
0Delete, cancel or archive. Ask first, or deny outright.
- No destructive actions.
Fixer in three steps.
- 01Your users connect FixerThey add their Fixer api key on Arc0 Connect, under your brand. It goes straight into the vault.
- 02You set the rulesReads run, and writes like “updates” can wait for the user to approve.
- 03Any agent can actYour agent calls Fixer through the Arc0 SDK or MCP, and so can Claude, ChatGPT and Cursor. Every call lands on the audit log.
await arc0.policies.set('fixer', { read: 'allow', write: 'ask', destructive: 'deny', }) # Claude Code: the same connection, one URL $ claude mcp add --transport http arc0 \ https://mcp.arc0.ai/u/u_8f2
How Fixer connects.
Users add their Fixer api key on Arc0 Connect. It is encrypted in the vault, never shown to the model, and each user can rotate or revoke it at any time.
The same Fixer connection serves your agent over MCP and your own backend over REST and the proxy, so a user connects once. How Arc0 handles credentials →
- AUTH
- API key
- CREDENTIALS
- Per-tenant encrypted vault
- MODEL SEES
- Results only, never credentials
- AUDIT LOG
- Every call, on every plan
Use Fixer from any agent.
ClaudeChatGPTCursor
Codex
VS CodeOpenAI Agents SDKClaude Agent SDK
Vercel AI SDK
Mastra
LangGraph
Fixer and Arc0, answered.
Can I use Fixer with Claude, ChatGPT or Cursor?
Yes. Connect Fixer to Arc0 once, then add your Arc0 MCP URL to Claude, ChatGPT, Cursor, Claude Code or any other remote-MCP client. Each assistant only gets the Fixer actions you allow.
How do users connect Fixer?
Users add their Fixer api key on Arc0 Connect. It is encrypted in the vault, never shown to the model, and each user can rotate or revoke it at any time.
Which Fixer actions can my agent take?
3 in total: 3 read, 0 write and 0 destructive. Your policies decide which of them each agent may call.
Can I make my agent read-only in Fixer?
Yes. Allow read actions and deny writes in the Fixer policy. Your agent can still look things up, and any write it attempts is blocked and logged.
Can my own backend call Fixer too?
Yes. The same Fixer connection is available over REST and through the Arc0 proxy, so your product and your agent share one connection per user.
Plug Fixer into your agent.
Your users connect Fixer once, under your brand. Your agent gets 3 actions behind your policies, with every call on the record.
Free to build · MCP + REST · Audit log on every plan