Looking for a Thunder Client alternative? I built one where free stays free

If you searched for a Thunder Client alternative, you probably hit the same wall I did: the most installed REST client for VS Code (7.4 million installs) sits at 2.39 stars, and the reviews explain why. Things that used to be free moved behind a paywall, including looking at your own request history. One review puts it plainly: "You must pay to look at a request you did in the past."

I did not want to leave VS Code for API work, and I did not want to rent access to my own data. So I built MailPal.

The promise first

MailPal exists because of one rule, and it is written into the listing like a contract:

The free tier is fully usable for a single user, forever
Unlimited requests, unlimited collections, unlimited local history
No account, no cloud, everything works offline
Paid only ever adds new value. It never gates access to your own data. If a license lapses, everything you made keeps working.

What you get

A native feeling request editor: auto-growing key/value rows like Postman, header autocomplete, color coded JSON editing with format and live validation
Collections stored as plain JSON in your workspace, so they diff, review, and share through git like any other code
Per collection variables with placeholders. Secret values go in the OS keychain through VS Code SecretStorage, never into files.
Syntax highlighted responses, an HTML raw/preview toggle (fully sandboxed), and a resizable request/response split
Import from Postman v2.1, Thunder Client, OpenAPI 3.x, and curl, so switching takes minutes
Simple per request assertions with pass/fail on every send
Unlimited local history with one click re-send

Full control over the wire

One thing I always missed in lightweight clients: knowing exactly what gets sent. MailPal surfaces every header the tool adds on its own (Content-Type from the body type, Authorization from the auth config, the HTTP engine defaults) with a note on where each comes from and how to override it.

The MCP part

MailPal ships a built in MCP server, registered with VS Code agent mode automatically. That means Copilot agent mode, Claude, Cursor, or any MCP client can list your saved requests, run them, and read the results. Ask your agent to "run the Create invoice request and tell me if the status changed" and it just works. As far as I know, no other REST client does this.

What paid adds

$4/month or $70 once. It adds AI request generation (describe a request in plain English, get it built) and MCP write tools so agents can create and edit requests. That is it. Your data is never part of the deal.