endorsedCompleted

x402 Facilitator Prototypes for xAI/X and Cal.com

Services Covered:

AI and Machine Learning • API Development • Custom Software Development

Industry

Financial Services

Duration

2 months

Budget

10K - 49K

Start Date

1 May 2025

Team Size

1-5 Employees

Engagement Model

Onshore

Project Capability Score (PCS)

77/100

Good

Project Capability Score (PCS) estimates how capable Boosty Labs is of successfully delivering a project like this, based on its past experience, track record, and ability to handle similar work. Learn more about PCS

Client

Coinbase Developer Platform

San Francisco, United States of America

Project Summary

Boosty Labs built two x402 facilitator prototypes that wrapped xAI/X APIs and the Cal.com scheduling API into on-chain, pay-per-use services with USDC settlement. The engagement delivered working prototypes, reusable scaffolding for future integrations, and automated tests that validated agent compatibility and reliable end-to-end settlement.

Key Challenges

Build an xAI prototype that exposes xAI and X APIs behind an x402 payment wrapper
Build a Cal.com prototype that converts scheduling and booking actions into on-chain pay-per-use operations using x402

Project Deliverables

xAI + X API x402 facilitator prototype (wrapper that exposes model inference and X APIs behind an x402 payment wrapper)
Cal.com API x402 facilitator prototype (wrapper exposing Cal.com scheduling/booking primitives behind x402)
Reusable scaffolding and blueprint for price quoting, payment payload generation, transaction verification, upstream API forwarding, and error handling with retries
Live automated tests validating agent compatibility and end-to-end USDC settlement

Project Solution

Boosty Labs developed two prototypes that wrap third-party APIs behind an x402-compliant payment facilitator. The work included creating a wrapper for xAI and selected X APIs and a wrapper for Cal.com’s REST API that return 402 Payment Required responses with a price quote and a signed USDC transaction payload, verify on-chain settlement, forward requests to upstream APIs after payment, and return responses to callers. They also delivered reusable scaffolding for quoting, payment payload generation, transaction verification, forwarding, error handling, and live automated tests to validate agent compatibility.

Project Outcome

Delivered two fully functional x402 facilitator prototypes (xAI + X API wrapper and Cal.com API wrapper)
Achieved end-to-end USDC on-chain settlement and protocol-compliant flows with successful payment verification in testing
Reduced integration time for new API categories from weeks to approximately 2–3 days and provided a reusable blueprint enabling 30–50% faster future integrations
Verified agent compatibility via live automated tests with acceptable latency (<1 second added overhead) and 100% payment verification accuracy in testing

Platforms

Tech Stack

REST API

Client Endorsement

Overall Review Rating

Timeliness

Cost Rating

Willing to Refer

Quality of Deliverables

“Boosty Labs delivered fully functional x402 facilitator prototypes, demonstrating the generalization of x402 across different API categories. The team provided a reusable scaffolding and verified agent compatibility through live automated tests. They delivered on time and were highly responsive.”
Kevin Leffew
GTM Lead
Date: 12/05/2025