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Zerobounce API

Give your agents access to Zerobounce API. Bring your own Zerobounce key, or skip the signup and pay per call from your Composio balance with Composio Instant.

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Zerobounce

Instant

ZeroBounce is an email validation and deliverability platform that detects invalid or risky email addresses. It helps businesses improve email marketing results by ensuring emails actually reach real people.

22 Tools

COMPOSIO INSTANT

What is Composio Instant?

Composio Instant lets your agent use paid APIs like Zerobounce without a separate account or API key for each one. New accounts start with $2 of free credit.

No Zerobounce account or key

Your agent calls Zerobounce through Composio, so there is nothing to sign up for, store, or rotate.

Pay per call, at cost

$0.019 per email validated; unknown results are free., paid from your Composio balance with zero markup.

Works in any agent

Claude, ChatGPT, Cursor, and other MCP clients, or your own code with the Composio SDK.

Works with your apps

Use Zerobounce with Gmail, Slack, Google Sheets, and 1,700+ other apps you connect.

AI ASSISTANTS

Connect the Zerobounce API to your AI assistant

Use Zerobounce from the AI assistant you already work in. Connect Composio once, then paste the prompt.

1
Open the Connectors menu
Use the button to open Claude's Add connector dialog with Composio filled in. Or click + in the message box, then Connectors, Add connector and Add custom connector.
Add Composio to Claude
2
Add the Composio MCP server
Name it Composio, paste the MCP server URL and click Add.
https://connect.composio.dev/mcp
3
Authorize in your browser
A browser window opens. Sign in to Composio to approve the connection.
4
Paste the prompt
Start a new chat and paste the prompt. Claude runs the call on Composio Instant.

1
Install the Composio plugin
Open Composio's plugin page in ChatGPT and click Install. Sign in to ChatGPT first if it asks.
Install in ChatGPT
2
Authorize in your browser
Connect the plugin, then sign in to Composio to approve the connection.
3
Turn on Composio in your chat
In a new chat, click +, then More, and select Composio.
4
Paste the prompt
Paste the prompt into that chat. ChatGPT runs the call on Composio Instant.

1
Install the Composio plugin
Open Composio in the Cursor marketplace, click Install Composio Plugin for Cursor and approve the connection in your browser.
Install in Cursor
2
Paste the prompt
Open the Agent chat and paste the prompt. Cursor runs the call on Composio Instant.

1
Add the Composio plugin
Open Composio's listing on x.ai and click Add to Grok Bot. When Grok Bot opens the plugin, click Add.
Add to Grok Bot
2
Authenticate
Go to Installed, open Composio and click Authenticate. Sign in to Composio and click Authorize.
3
Paste the prompt
Paste the prompt into your bot's chat. Grok Bot runs the call on Composio Instant.

1
Paste the setup prompt
Copy this into your Hermes chat. Hermes adds the Composio MCP server for you.
Set up Composio from composio.dev/hermes
2
Authorize in your browser
A browser window opens. Sign in to Composio to approve the connection.
3
Paste the prompt
Start a new chat and paste the prompt. Hermes runs the call on Composio Instant.

ClaudeNew chat

Paste this prompt

Use ZeroBounce through Composio Instant to validate sales@acme.com. Return its deliverability result and domain details.

What success looks like

ZEROBOUNCE_VALIDATE_EMAIL

Your assistant runs ZeroBounce and replies with the deliverability result and domain details for sales@acme.com.

Runs on Composio Instant

SDK

Use the Zerobounce API in your code

Call Zerobounce from your own agent with the Composio SDK. Four steps and one tool call.

1
Set up Composio
Turn on Instant Toolkits in your project settings and check your prepaid balance in Billing. Then set your API key.
export COMPOSIO_API_KEY="your_composio_api_key"
2
Install the SDK
The Python SDK needs Python 3.11 through 3.15.
The TypeScript SDK is ESM-only and needs Node.js 22.22.3 or newer.
pip install composio
npm install @composio/core
3
Run the call
Create a session that keeps Instant to this toolkit and reports the charge, then run the tool on the Instant account.
ZEROBOUNCE_VALIDATE_EMAIL
4
Read the response
When the call runs on Instant, the response includes its charge: the amount as an exact USD decimal string, the currency and charged_by.

agent.py

from composio import Composio

composio = Composio()

session = composio.sessions.create(
    user_id="user_123",
    toolkits=["zerobounce"],
    instant={
        "toolkits": {"enable": ["zerobounce"]},
        "return_instant_charge": True,
    },
)

result = session.execute(
    "ZEROBOUNCE_VALIDATE_EMAIL",
    arguments={
        "email": "sales@acme.com",
    },
    account="instant_account",
)
print(result)
print("Instant charge:", result.instant_charge)

agent.ts

import { Composio } from "@composio/core";

const composio = new Composio();

const session = await composio.create("user_123", {
  toolkits: ["zerobounce"],
  instant: {
    toolkits: { enable: ["zerobounce"] },
    returnInstantCharge: true,
  },
});

const result = await session.execute(
  "ZEROBOUNCE_VALIDATE_EMAIL",
  {
    "email": "sales@acme.com"
  },
  { account: "instant_account" },
);
console.log(result);
console.log("Instant charge:", result.instantCharge);

response

{
  "data": "<validation result>",
  "successful": "<true or false>",
  "instant_charge": {
    "amount": "<usd amount>",
    "currency": "USD",
    "charged_by": "<provider>"
  }
}

TOOLS

Available Zerobounce API tools

6 Zerobounce tools run on Instant, priced per call with no Zerobounce key. Tools marked Your key need your own Zerobounce account.

Action	Tool slug	What it does	Availability
Validate Email	ZEROBOUNCE_VALIDATE_EMAIL	Check an email address's deliverability and domain details before sending.	Instant$0.019 per email validated; unknown results are free.83% off
Batch Validate	ZEROBOUNCE_BATCH_VALIDATE_EMAILS	Validate up to 200 email addresses in a real-time batch.	Instant$0.019 per email validated; unknown results are free.83% off
Evaluate List	ZEROBOUNCE_LIST_EVALUATOR	Check an email list's quality before full validation.	Instant$0 per request
Search Domain	ZEROBOUNCE_DOMAIN_SEARCH_SINGLE	Find common email address formats for a domain or company name.	Instant$0.39 per email format found; free if none is found.
Score Email	ZEROBOUNCE_AI_SCORING_SINGLE	Score a single email address with ZeroBounce AI.	Instant$0.019 per email scored.83% off
Get Activity Data	ZEROBOUNCE_ACTIVITY_DATA	Tool to get activity data (opens, clicks, etc.) for a given email.	InstantEstimated $0.019 per matched Activity Data record.
Upload Validation File	ZEROBOUNCE_SEND_FILE	Upload a file for bulk email validation.	Your key
Check File Status	ZEROBOUNCE_GET_VALIDATION_FILE_STATUS	Check processing status for a bulk email-validation file.	Your key
Download Results	ZEROBOUNCE_GET_VALIDATION_FILE	Download results for a completed bulk email-validation file.	Your key

Instant prices are Zerobounce's list prices with 0% markup, paid from your Composio balance and updated every hour. Instant calls also count toward your plan's tool calls. See all plans on the pricing page.

USE CASES

Zerobounce API use cases and example prompts

Copy a prompt into your agent. Each one uses Zerobounce with apps you connect through Composio.

Clean the campaign contact list
Use ZeroBounce to validate up to 200 addresses in my Acme Campaign Contacts sheet in Google Sheets. Add the validation results to the matching rows, then post a summary in Slack's #marketing channel.
Apps used: Zerobounce, Google Sheets, Slack
Review a list before import
Use ZeroBounce to evaluate the Acme webinar signup list in my Google Drive before I import it into HubSpot. Add the list quality findings to the Acme campaign record in HubSpot, and tell me whether the list is ready for full validation.
Apps used: Zerobounce, Google Drive, HubSpot
Check address formats for Acme
Use ZeroBounce to find common email address formats for acme.com. Add the formats to the Acme company record in HubSpot, then draft a Gmail message to my sales team with the findings.
Apps used: Zerobounce, HubSpot, Gmail
Review a shared inbox address
Use ZeroBounce AI scoring to score sales@acme.com before we use it as the reply-to address for a campaign. Add the result to my Sender Review sheet in Google Sheets, then share a short summary in Slack's #marketing channel.
Apps used: Zerobounce, Google Sheets, Slack

TROUBLESHOOTING

Zerobounce API troubleshooting

Still stuck? The Instant tools docs cover limits, charges and session settings.

Set email_address_column to the 1-based column index that contains the addresses when calling ZEROBOUNCE_LIST_EVALUATOR.

Split email_batch into groups of up to 200 addresses before calling ZEROBOUNCE_BATCH_VALIDATE_EMAILS.

Check its availability in the tools table. If it runs on Instant, check that Instant Toolkits is on for your project, your session allows the action and you use the latest toolkit version.

Your Composio balance is empty. Add funds in Billing if your plan supports it, or connect your own Zerobounce account.

Check credential_source and instant_charge in the Composio execution log.

COMPOSIO INSTANT

Other tools on Instant

These tools also run on Composio Instant and use the same Composio balance.

Toolkit marketplace

Ahrefs

Api KeyOauth2

Ahrefs is an SEO and marketing platform for site audits, keyword research, and competitor insights. It helps you improve search rankings and drive organic traffic.

Hunter

Api Key

Hunter is an email marketing platform for lead generation and contact data enrichment. It helps you quickly find and verify professional email addresses to boost outreach.

ScrapeCreators

Api Key

ScrapeCreators is a scraping service that extracts public profiles, posts, videos, comments, ads, and other content from social platforms. Use it to quickly collect structured public social data for analysis, monitoring, and content research.

Firecrawl

Api Key

Firecrawl automates large-scale web crawling and data extraction. It helps organizations efficiently gather, index, and analyze content from online sources.

Start with Zerobounce.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Zerobounce tool your agent needs.Free to start.

Start building

Zerobounce API

What is Composio Instant?

No Zerobounce account or key

Pay per call, at cost

Works in any agent

Works with your apps

Connect the Zerobounce API to your AI assistant

Open the Connectors menu

Add the Composio MCP server

Authorize in your browser

Paste the prompt

Install the Composio plugin

Authorize in your browser

Turn on Composio in your chat

Paste the prompt

Install the Composio plugin

Paste the prompt

Add the Composio plugin

Authenticate

Paste the prompt

Paste the setup prompt

Authorize in your browser

Paste the prompt

Use the Zerobounce API in your code

Set up Composio

Install the SDK

Run the call

Read the response

Available Zerobounce API tools

Zerobounce API use cases and example prompts

Clean the campaign contact list

Review a list before import

Check address formats for Acme

Review a shared inbox address

Zerobounce API troubleshooting

List evaluation misses the email addresses in my CSV

Batch validation rejects a large email list

An action asks you to connect Zerobounce

You get HTTP 402 with Metering_WalletBalanceExhausted

You're not sure which account was charged

Other tools on Instant

Ahrefs

Hunter

ScrapeCreators

Firecrawl

Start with Zerobounce.It takes 30 seconds.