Create and Use Farcaster Signers

I got nerdsniped on Farcaster today.

@keccers.eth was talking about the Sent from coinbasewallet tag. You usually only see these on third-party clients, which is why @artlu having his own stands out on the timeline.

My curiosity was piqued, I started poking around, and soon I had landed somewhere between

and

Nerdsniped. @stevedylandev.eth joined the conversation with the resources he'd already built.

• Cast Keys: https://github.com/stevedylandev/cast-keys
• Mast-cli: https://github.com/stevedylandev/mast-cli

He even posted a video on Youtube as a walkthrough for the process: https://www.youtube.com/watch?v=rPr8A9Ntp1E

How to post with your own "sent from …​" tag

1. Clone Cast Keys and configure it

   git clone https://github.com/stevedylandev/cast-keys
   cd cast-keys
   npm install                       # install deps for Cast Keys
   cp .env.v.sample .env.local
   

   Edit .env.local:

   DEVELOPER_FID=<FID that should appear in "sent from …">
   DEVELOPER_MNEMONIC=<that handle's 12-word phrase>
   

2. Start Cast Keys and create a signer

   npm run dev
   

   Open http://localhost:3000, click Create Signer, scan the QR in Warpcast, pay the Warps, and copy the private key (omit the leading 0x).

3. Install the Mast CLI

   Script (one-liner)

   curl -fsSL https://stevedylan.dev/mast.sh | bash
   

   Homebrew

   brew install stevedylandev/mast-cli/mast-cli
   

4. Authorise Mast with your signer

   mast auth
   # 1 – enter your personal FID
   # 2 – paste the private key
   

5. Post from the terminal

   mast new
   # type the message → Enter
   # optional: up to two URLs → Enter
   # optional: channel → Enter
   

6. Revoke a signer when necessary Warpcast → Settings → Advanced → Manage Connected Apps → select the key → Delete (no cost).

Why run Cast Keys locally? The hosted tool at castkeys.xyz always uses @castkeys' credentials, so every post shows "sent from castkeys." Running it yourself puts your name on the marquee and keeps the keys in your own hands.

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It works. I can cast with a custom signer. Next step: a vanity account.