How to Buy an eSIM with Claude
To buy an eSIM with Claude you give it one URL and it can read our whole catalogue — live plans, the real total, the actual country list behind each regional plan. Setup is a single field, there's no API key, and unlike most assistants it works on the free plan. What Claude can't do is pay. It hands you a link and you take it from there, which is the point.
Pick your setup path
Claude reaches outside services through MCP, and Siima runs a public MCP server at https://api.siima.online/mcp. How you add it depends on where you use Claude. All three paths end at the same server and the same five tools.
| Where you use Claude | How to add Siima |
|---|---|
| Claude app, claude.ai, mobile | Customize › Connectors › + › Add custom connector. Free, Pro and Max. |
| Claude Code | One terminal command (below). Nothing to click. |
| A Team or Enterprise workspace | An owner adds it once in Organization settings; everyone then clicks Connect. |
If you came here from the ChatGPT version of this guide, the main difference is that Claude doesn't hide custom connectors behind a developer-mode switch on a paid tier. You add a URL and you're done.
Adding the connector in the Claude app
| Step | What to do |
|---|---|
| 1 | Open Settings and go to Customize, then Connectors |
| 2 | Click the + and choose Add custom connector |
| 3 | Paste https://api.siima.online/mcp as the remote MCP server URL and name it Siima |
| 4 | Leave the OAuth fields under Advanced settings empty — there is no key or login to add |
| 5 | Click Add. Claude reads the tool list straight away; you should see five tools |
The free plan allows one custom connector at a time, so if you already have one you'll swap it out. Pro and Max have no such cap. Anthropic occasionally moves these menus, and older write-ups still say Settings › Connectors; if the labels don't match what you see, the thing to look for is a Connectors list with an option to add your own server by URL.
A remote connector is called from Anthropic's infrastructure, which has two practical consequences. The good one: add it once on your laptop and it works in the mobile app too, which is handy when you realise at the airport that you forgot to buy data. The one to know about: the request doesn't come from your home IP, so prices come back in whatever currency you ask for rather than being guessed from your location. Ask for euros if you want euros.
Claude will ask you to approve a tool call before it runs one, at least the first few times. Allowing the read-only ones is harmless — searching plans is the same thing as browsing the destinations page. The only tool that creates anything is the checkout-link one, and a link on its own costs nothing.
In Claude Code, one line
If you live in a terminal:
claude mcp add --transport http siima https://api.siima.online/mcp
Run /mcp inside a session to confirm it connected. Add --scope user if you want it available in every project rather than just the current one. There's no sign-in step, because the server has no authentication to sign in to.
Other MCP clients work the same way — Cursor, Codex, anything that accepts a streamable-HTTP server URL. The Siima for AI agents page has copy-paste lines for each.
What to ask once it's connected
Give it the trip, not a product name. Claude is better at the judgement part — how much data you'll actually get through — than at guessing which plan you had in mind.
The East Africa one is a good test of whether the connector is actually working. Without it, an assistant will reason from the region's name and guess. With it, Claude calls list_regions, reads which countries each coverage area really contains, and tells you. Our region names don't always match the atlas — there's a whole section on that in the multi-country guide.
One claim to check it on: ask whether an unlimited plan is really unlimited. The honest answer, which the connector will give you, is 1 GB a day at full speed and then 512 kbps until the day rolls over. If Claude tells you something else it's answering from memory rather than from the catalogue — check the connector is switched on for that chat.
What happens when you say “buy it”
Claude doesn't buy anything. It creates a checkout link for the plan you settled on and gives it to you:
Some eSIM shops are building the other model, where the assistant holds a pre-funded balance and completes the purchase by itself. We chose the handoff on purpose. An eSIM can't meaningfully be returned once it's installed, and an assistant that read “Austria” as “Australia” shouldn't be able to spend your money proving it. The two models are compared properly in the eSIM for AI agents guide. New to the QR step? The install guide covers it — do it before you fly, switch the line on when you land.
Set it up once in a Project
If you travel often, the repetitive part isn't the buying, it's restating your preferences every time. Make a Project, enable the Siima connector on it, and put the standing stuff in the project instructions: your currency, whether you tether, that you want the fee-inclusive total rather than the headline price, that you'd rather have a slightly bigger plan than top up mid-trip. After that “ten days in Lisbon” is enough of a prompt.
It's also a decent place to keep the trip itself — flight dates, which days you're out of the city, where the SIM-free week is. Claude sizes data better when it knows you'll be on hotel Wi-Fi for four of the ten days.
For a team
On Team and Enterprise, a workspace owner adds the connector once — Organization settings › Connectors › Add, hover Custom, pick Web, paste the URL — and it shows up in every member's Connectors list for them to Connect. Nobody has to be told a URL or walked through a settings menu.
That's more useful than it sounds for anyone who books travel for other people. The person flying doesn't need an account, an app, or even to be in the same Claude workspace: the checkout link takes whichever email address you give it, and the QR code goes straight to them. If you're buying for a whole team regularly, Siima for business adds shared billing and bulk purchasing on top.