Vapi AI voice agent development

A voice agent that can work with your systems

Conversation is one part of the product. Your agent also needs reliable tools, clear rules for business actions and a backend that can handle failures. I develop the Vapi assistant, API integrations and surrounding software together.

What your Vapi project can include

• Assistant configuration and conversation workflow design
• Custom tools and authenticated webhook endpoints for your backend
• WooCommerce, CRM, scheduling and other business API connections
• Call events, reporting and operator workflows
• Validation, duplicate-action protection, failure handling and scenario testing
• Deployment, operating documentation and project handoff

The scope starts with your use case: what the agent should know, what it can change and when your team should take over.

Custom Vapi tools: from a caller request to an API result

For each tool, I define the action, required parameters and the response the assistant needs. The Vapi tool connects to an authenticated backend endpoint; that endpoint validates the request and communicates with your business system.

For example, an appointment lookup needs a service, date and business location. A booking action also needs caller identification, current availability and a clear confirmation step. The backend returns an explicit result so the assistant can confirm success or explain the next step.

When the API is unavailable or the caller supplies incomplete information, we define a recovery path. For actions that change records, we also address repeated requests so a retried tool call does not create an unintended second action.

Fix Vapi booking, tool calls and staff handoff

If your Vapi assistant offers occupied slots, confirms an appointment without a calendar entry or loses details before a transfer, send examples of those calls. I review tool definitions, request parameters, backend responses and call events to locate where the action fails. A successful webhook alone does not prove that the assistant used the result correctly.

1. Map the assistant's current tools and the business actions they represent.
2. Define input validation, customer context and API response handling.
3. Connect call events to reporting and staff follow-up where required.
4. Check end-to-end scenarios, including missing data and failed API calls.

Provider migration when your workflow requires it

I can also assess a Retell-to-Vapi migration: map tools, call events and application dependencies, retain reusable backend rules and verify the required call scenarios before switching.

Planning your Vapi integration

Can you build with Vapi if the existing projects use Retell?

Yes. I can develop with Vapi or Retell AI according to your product requirements. The implementation covers the provider-specific assistant and tool interfaces as well as the business logic, backend and user experience around them.

Can you connect Vapi to an existing WooCommerce store or CRM?

Yes. I map the data and actions the agent needs, then build the API layer and tools for that workflow. The approach depends on your catalogue, customer identification, ordering rules and the APIs available in your current software.

Can you move an existing voice workflow between providers?

I can assess and implement a migration. Prompts, tools, call events and any provider-specific behaviour need to be mapped and tested against your existing scenarios; the surrounding application may also need changes.

What should I send to get started?

Your desired call workflow, current tools and APIs, example customer interactions and any timing constraints. If you already have a Vapi assistant, describe what works and what needs improvement.

Explore related work

See the Voice AI development service and Retell AI development, plus the Slivo voice commerce architecture breakdown.

Project delivery and handover

We agree on the deliverables and acceptance scenarios before implementation. The handover covers the custom source code, configuration, deployment instructions and the checks used to verify the workflow.

Your team controls the project accounts and credentials. I document external services, usage assumptions and recurring costs, and show how to review failures and change the configuration. Ongoing support can be scoped separately.