Locus product guide · Updated November 10, 2026

Best ChatGPT MCP servers and how to add a custom one

ChatGPT connects to MCP servers as plugins. Good picks from the plugin directory are Exa and Firecrawl for web research, Context7 for code docs, Alpha Vantage for market data and Semrush for SEO. To add any other server, open chatgpt.com/plugins, select the plus button, choose Add custom MCP server, enter the URL and pick OAuth or no authentication. Custom servers are added on ChatGPT for the web, must use SSE or streaming HTTP, and ask before write actions.

Setup, step by step

Step 1
Open ChatGPT Plugins on the web
Go to chatgpt.com/plugins in a browser. Workspace permissions and security settings, including Lockdown, decide whether you can add custom servers.
Step 2
Choose Add custom MCP server
Select the plus button, then Add custom MCP server. Enter a name and, if you like, a description.
Step 3
Enter the connection
Under Connection, paste the server URL, including its /mcp path. For a private server, select Tunnel and pick a Secure MCP Tunnel instead.
Step 4
Set up authentication
Pick OAuth, No authentication, or OAuth or no authentication. Review the risk warning and select I understand and want to continue.
Step 5
Create and install the plugin
Select Create as a plugin and review the tools ChatGPT found. The plugin appears under your personal plugins or your workspace. Install it, then call it in a chat.

Which MCP servers work best in ChatGPT?

Start with plugins already in the directory, since they install with a click. ChatGPT and Codex share that directory, so the same plugins show up in both. Checked November 10, 2026.

Which MCP servers work best in ChatGPT?
Plugin or server	Job	How to add	Vendor account
Exa	Web search and research	Plugin directory	Exa's hosted server runs without a key at a free rate limit
Firecrawl	Search, scrape and parse pages	From the directory	Hosted server is keyless within daily limits
Context7	Current library and API docs	Directory plugin	Anonymous use; a free key lifts rate limits
Alpha Vantage	Stock quotes, fundamentals, news sentiment	Directory, for any free or paid ChatGPT account	Free Alpha Vantage key, 25 requests a day
Semrush	Keyword, domain and backlink data	Listed in the directory	Paid Semrush plan with API units
HubSpot, Notion, Supabase, Airtable, GitLab, Vercel	Your own work data	Directory, with Sign in with ChatGPT	An account at each service
Locus Pro	Paid APIs from one credit balance	Add custom MCP server	Locus account, OAuth

Can ChatGPT use a local MCP server?

Not by URL. ChatGPT reaches custom servers over the internet with SSE or streaming HTTP, so a server that runs as a local command, such as Playwright, will not connect as is.

The fix is a Secure MCP Tunnel. It lets ChatGPT reach a private stdio or HTTP server without exposing it to the public internet. A development tunnel works for testing too.

What happens when ChatGPT calls a tool that changes data?

ChatGPT asks first. Write actions need your confirmation by default, and you can expand any call to see the full JSON input and output. ChatGPT treats a tool as read-only only when the server marks it with readOnlyHint.

You can tell ChatGPT to remember an approval for the rest of one conversation. A new conversation, or a refresh, asks again. OpenAI warns that an untrusted server can steal data or trick ChatGPT into changing or deleting it, so add only servers you trust.

How do you use paid APIs in ChatGPT with Locus Pro?

Add the Locus Pro MCP server as a custom plugin with OAuth. ChatGPT can then search the catalog, see each price, and call paid APIs from one credit balance, with no account at each vendor. The setup guide walks through it. To keep the tool list short, you can add a single-job Locus server instead, such as https://finance.mcp.paywithlocus.com for market data. Each one needs its own sign-in.

Prices below are live catalog prices. Prices checked November 10, 2026. 1,000 credits equal $1. Search, describe and balance checks are free.

If the free Alpha Vantage or Exa plugins cover your volume, use them. Locus Pro pays off when one chat needs several paid vendors.

How do you use paid APIs in ChatGPT with Locus Pro?
Job in ChatGPT	Locus endpoint	Credits per call	Price
Cited search answer	perplexity/search	5.8	$0.0058
Read a page as text	firecrawl/scrape	1 to 38.6, usually 1	Usually $0.001
Find people at a company	apollo/people-search	2 fixed	$0.002
Check an email address	hunter/email-verifier	5.1 fixed	$0.0051
Stock quote	alphavantage/global-quote	5.1 flat	About $0.0051
Keyword search volume	dataforseo/search-volume	90.9 to 9,090	$0.0909 to $9.09

How do you choose MCP servers for ChatGPT?

Prefer a directory plugin when one exists. It installs in one click and gets updates through OpenAI review. Add a custom server only for tools the directory lacks.

Research and browsing: Exa or Firecrawl.
Market data: Alpha Vantage, within its free 25 requests a day.
SEO data you already pay for: Semrush.
Company tools such as HubSpot or Notion: the directory plugin with Sign in with ChatGPT.
Several paid data vendors behind one sign-in: Locus Pro as a custom server.
Anything that runs only on your machine: a Secure MCP Tunnel, or a host such as Codex that runs local servers.

Best MCP servers for Codex

Frequently asked questions

Can I add a custom MCP server in the ChatGPT desktop or mobile app?

OpenAI's guide says to add custom MCP servers in ChatGPT on the web. Plugins in general work in ChatGPT on the web, desktop and mobile once installed.

Does a custom MCP server need search and fetch tools to work in ChatGPT?

No. Custom servers can expose any tools, including write actions. ChatGPT asks for confirmation before tools that are not marked read-only.

Do ChatGPT plugins also work in Codex?

Public plugins do. ChatGPT and Codex use one plugin directory, so a plugin you find in one is listed in the other. The Codex IDE extension is the exception, since it does not support plugins.

What does Sign in with ChatGPT share with a partner?

Your name, email address and profile picture when available. It does not give the plugin access to your data or approve actions. You review and approve the plugin permissions as a separate step.

Implementation references

Use these first-party references for current request contracts and account requirements. Tool availability, prices, and negotiated terms can change.

Sources

Third-party details were checked on November 10, 2026. Vendors change pricing and features often, so confirm on their site before you decide.

Setup, step by step

Open ChatGPT Plugins on the web

Choose Add custom MCP server

Enter the connection

Set up authentication

Create and install the plugin