Claude in Excel: Anthropic API Key and Bulk Prompts

Claude is a family of AI models by Anthropic. People like it for careful work with long texts, precise instruction following and natural, non-template language. With the !SEMTools add-in, you can connect Claude right to Excel and process whole columns with it: classify, rewrite, translate, extract data from text.

I’ll show you how to get an API key, save it in the add-in, send prompts in bulk, and which details are worth knowing in advance.

What Claude can do in Excel

Typical tasks Claude handles well on table data:

rewriting and shortening texts: product descriptions, titles, abstracts;
classification and tagging: review sentiment, product category, support ticket type;
extracting data from free text: brand, model, size, city;
translating texts and adapting them for another audience;
proofreading texts and checking style consistency.

Install !SEMTools to use Claude in Excel

If your Excel doesn’t have the !SEMTools tab yet, first download and install the !SEMTools add-in. Follow the guide carefully and come back here. The Claude menu is on the !SEMTools tab: Web (Scraping, SEO, PPC) → APIs → Anthropic Claude.

How to get a Claude API key in the Anthropic Console

The key is issued in the Anthropic developer console (Claude Console). Sign up, add credits to your API balance, then create a new key in the API Keys section and copy it. The key is shown only once, so save it right away.

The API is billed separately from a Claude.ai subscription: a Pro or Max plan doesn’t include API usage. Prices depend on the model and on the number of tokens in the prompt and the answer; check the current rates on the Anthropic pricing page.

Save the Claude API key and choose a model

In the Anthropic Claude menu, choose Settings (model, API key). A form opens with a field for the key and a list of models:

claude-sonnet-5 — the default model, a good balance of quality, speed and price;
claude-opus-5 — for complex tasks and analysis;
claude-haiku-4-5 — fast and inexpensive, for simple bulk tagging;
claude-fable-5-1 — a Mythos-class model that sits above Opus: the most capable and the most expensive option in the list.

Paste the key, choose the model and click OK. The add-in remembers both. Until a key is saved, processing stops with the message “Claude API key is missing. Check settings.”

Just in case: the key is stored right in the add-in file. If you share your .xlam file with a colleague, they’ll be able to use your API access and your balance.

Process cells in bulk with Claude

The Anthropic Claude menu has two processing commands:

Process every prompt in selected range (1-column): each selected cell is a ready prompt. The add-in asks for a timeout between requests in seconds, sends the cells to Claude one by one and writes the answers in their place.
Process selected cells (input prompt prefix): the add-in asks for one prompt, for example “Rewrite the product description in 2 sentences, no exclamation marks”. The prompt is added to the content of every cell, so the cells can hold just the data: product names, reviews, website URLs.

Before, the second scenario meant you had to add text to all cells first and only then send the resulting prompts. The prompt prefix saves you that step.

Prompt	Cell	Claude’s answer
Classify the request: shipping, payment, return, other. Return one word	I was charged twice, please refund one payment	payment
Extract the size and color, comma-separated	Men’s T-shirt, cotton, navy blue, XL	XL, navy blue
Shorten to 60 characters, keep the meaning	Wireless headphones with active noise cancellation and up to 30 hours of battery life	Wireless noise-canceling headphones, 30-hour battery

Since the answers replace the source cells, copy the column first if you want to keep the original data next to the results.

In the free version of !SEMTools, the prompt prefix command processes about 2/3 of the cells and replaces the rest with “!SEMTools – available in full version”. No API request is made for these cells, so no money is spent on them.

Claude response length limit

In the Anthropic Claude menu, the answer length is limited to 1,024 tokens, about 700–800 words. That’s plenty for tagging, data extraction and short texts. But if you ask Claude to write an article or a long description, the answer may get cut off. For long texts, use Claude models through OpenRouter, see below.

Claude models via OpenRouter in Excel

Claude models are also available in the OpenRouter catalog. This is handy if you already have an OpenRouter key and want to compare Claude with models from other vendors without opening one more account:

in the OpenRouter.ai menu, choose Input and save token and paste your OpenRouter key;
choose Select model and pick a Claude model, its ID starts with anthropic/;
select the cells and run Run selected cells as independent prompts or Process selected cells (input prompt).

The add-in doesn’t limit the answer length here, so this route suits long texts better. The price per token is close to Anthropic’s own, but you top up only one balance for all models.

Why Claude isn’t responding in Excel: common errors

“Claude API key is missing. Check settings.” — the key isn’t saved. Open Settings (model, API key), paste the key and click OK.
“API Error: 401” — the key is wrong or revoked. Create a new one in the Anthropic Console.
“API Error: 400” mentioning your credit balance — the API balance has run out.
“API Error: 429” — too many requests too fast. Increase the timeout between requests.
The answer stops mid-sentence — the length limit kicked in. Ask for a shorter answer or use OpenRouter.

Send whole columns to Claude right from Excel: one prompt for all cells, answers in place, no copying into a chat window.
!SEMTools solves this and hundreds of other tasks in a couple of clicks!

Download !SEMTools

Summary: when to choose Claude in Excel

I hope you found what you were looking for on this page and were able to connect Claude to Excel. For short tasks on cells, the Anthropic Claude menu is enough: save the key, choose the model, run a prompt prefix on the column. For long answers, or to switch between vendors with one key, use Claude models through OpenRouter. If the task needs fresh data from the web, take a look at Perplexity in Excel.

Other AI tools in Excel

!SEMTools works with more than one AI model. See also: