# Fiber AI, free, Cardless API trial, POST /v1/contact-details/batch/start, Start batch contact details, full: Email finder API

> Starts fetching contact details for multiple people (up to 2000) in batch. This is an asynchronous task, use the polling endpoint to check progress and get results.

Fiber AI's email finder API on its Cardless API trial plan. It costs $0.00 per 1,000 emails. It returns 3 of the 10 key fields we check: Verification, Personal email, LinkedIn URL.
We rank 1,285 plans by price. [ClearBounce's $3.20 monthly plan](https://datacircle.dev/find-email-apis/clearbounce/3-20-monthly/llms.txt) costs the least per 1,000 emails: as little as $0.00074. ClearBounce's $3.20 monthly plan covers up to 4,320,000 emails a month at no extra cost.
[ClearBounce's $4 pack](https://datacircle.dev/find-email-apis/clearbounce/4-pack/llms.txt) covers any number of emails. ClearBounce's $4 pack costs more to start than ClearBounce's $3.20 monthly plan.
[GetProspect](https://datacircle.dev/find-email-apis/getprospect/399-monthly-growth-50k-post-v2-email-find/llms.txt), [OrbiSearch](https://datacircle.dev/find-email-apis/orbisearch/207-pack-enterprise-post-v1-email-lookup/llms.txt) and [DataForB2B](https://datacircle.dev/find-email-apis/dataforb2b/499-monthly-growth-post-enrich-profile-5000000-results-a-month/llms.txt) are the best email finder API providers in our benchmark.

- This page: https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start-start-batch-contact-details-full
- [Best email finder API in 2026](https://datacircle.dev/best-email-finder-api.txt)
- Get it: https://www.fiber.ai/pricing
- Request: `POST https://api.fiber.ai/v1/contact-details/batch/start`, Start batch contact details, full
- API key: with the plan, on https://www.fiber.ai/pricing
- Its API docs: https://api.fiber.ai/ai-docs/startBatchContactDetails.md
- Sold by: Fiber AI (https://www.fiber.ai)
- Checked: 2026-10-23

## In the answer

- Completeness: 30%
- Verification: ✓
- Personal email: ✓
- LinkedIn URL: ✓

## Price

- $ per 1,000 emails: $0.00
- Per: result
- Billing: free

## Aggregators

- Aggregators: none

## Not found

- $ per 1,000: $0.00

## In their words

- Their pitch: Starts fetching contact details for multiple people (up to 2000) in batch. This is an asynchronous task, use the polling endpoint to check progress and get results.

## Data

- Keep data: a limited, non-exclusive, non-transferable, non-sublicensable right to (A) view and store the Prospect Data [...] Prospect Data and Usage Data are Confidential Information of Fiber AI. [...] After any expiration or termination of these Terms, or at any time upon request from Fiber AI, Customer will immediately return or destroy (at Fiber AI's sole direction) all materials or media containing any Confidential Information
- Use data: solely for purposes of conducting business-to-business sales, marketing, or business development activities and for Customer's other internal business purposes (the "Permitted Uses"). Customer may not resell, transfer, assign, or sublicense Customer's rights under these Terms to any third party or use the Services to run an outsourcing business or provide services for the benefit of any third party. [...] Customer (A) will not, and will ensure that Customer Personnel do not, incorporate any Prospect Data into Customer's products or services or otherwise resell, sublicense, or distribute any Prospect Data, (B) will not [...] present the Prospect Data so that it appears to be made available by any third party, (C) will process all Prospect Data in accordance with Laws, including Privacy and Data Laws [...] (F) not use the Services, including Prospect Data, to determine a consumer’s eligibility for (i) credit or insurance for personal, family or household purposes, (ii) employment or (iii) a government license or benefit or (iv) any other purpose governed by the Fair Credit Reporting Act [...] Customer will not [...] (h) develop any scripts or software applications that interact with or integrate with the Services unless first authorized in writing by Fiber AI [...] The Services are currently authorized to be used only in the United States to facilitate business-to-business sales, marketing, or business development communications with individuals in the United States

## Plan

- Pay: $0
- You get: 100 credits
- Enough for: 20 results, once
- Expires: when the 7 days pass without a card, the trial ends

## Rate limit

- Per second: 0.5
- Batch: 2,000

## Speed

- Answer: by polling or webhook

## The call

- You send: personDetails[].linkedinUrl.value. Optional: enrichmentTypes.getWorkEmails, enrichmentTypes.getPersonalEmails "true", enrichmentTypes.getPhoneNumbers "true"
- Method: POST
- Path: /v1/contact-details/batch/start

## About the plan

- Plan: Cardless API trial
- Who can get it: anyone with a work email, one trial per company domain, to use only in the United States

## The 8 fields the plan's answer can hold

LinkedIn URL, email, email type, email status, exhaustive, personal email, phone number, phone type

## Fiber AI's plans (9)

- [Fiber AI, free, Cardless API trial, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $0.00 per 1,000, 30% complete
- [Fiber AI, free, 7-day free trial, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/free-7-day-free-trial-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $0.00 per 1,000, 30% complete
- [Fiber AI, top-up from $3, Pay-as-you-go, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/top-up-from-3-pay-as-you-go-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $150.00 per 1,000, 30% complete
- [Fiber AI, $300 monthly, Prospector, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/300-monthly-prospector-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $100.00 per 1,000, 30% complete
- [Fiber AI, $900 monthly, Growth, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/900-monthly-growth-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $90.00 per 1,000, 30% complete
- [Fiber AI, $2,400 monthly, Enterprise, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/2400-monthly-enterprise-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $80.00 per 1,000, 30% complete
- [Fiber AI, $3,000 yearly, Prospector, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/3000-yearly-prospector-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $83.333 per 1,000, 30% complete
- [Fiber AI, $9,000 yearly, Growth, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/9000-yearly-growth-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $75.00 per 1,000, 30% complete
- [Fiber AI, $24,000 yearly, Enterprise, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/24000-yearly-enterprise-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt): $66.667 per 1,000, 30% complete

## Fiber AI's calls for this API (10)

- `POST /v1/contact-details/basic-work-email`: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/basic-work-email](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-basic-work-email/llms.txt)
- `POST /v1/contact-details/lite`: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/lite](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-lite/llms.txt)
- `POST /v1/contact-details/single`, Reveal contact details (standard): [Fiber AI, free, Cardless API trial, POST /v1/contact-details/single, Reveal contact details (standard)](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-single/llms.txt)
- `POST /v1/contact-details/single`, Reveal contact details (standard), full: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/single, Reveal contact details (standard), full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-single-reveal-contact-details-standard-full/llms.txt)
- `POST /v1/contact-details/turbo/sync`, Reveal contact details (turbo): [Fiber AI, free, Cardless API trial, POST /v1/contact-details/turbo/sync, Reveal contact details (turbo)](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-turbo-sync/llms.txt)
- `POST /v1/contact-details/turbo/sync`, Reveal contact details (turbo), full: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/turbo/sync, Reveal contact details (turbo), full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-turbo-sync-reveal-contact-details-turbo-full/llms.txt)
- `POST /v1/contact-details/batch/start`, Start batch contact details: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/batch/start, Start batch contact details](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start/llms.txt)
- `POST /v1/contact-details/batch/start`, Start batch contact details, full: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt)
- `POST /v1/contact-details/exhaustive/start`, Start exhaustive contact details reveal: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/exhaustive/start, Start exhaustive contact details reveal](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-exhaustive-start/llms.txt)
- `POST /v1/contact-details/exhaustive/start`, Start exhaustive contact details reveal, full: [Fiber AI, free, Cardless API trial, POST /v1/contact-details/exhaustive/start, Start exhaustive contact details reveal, full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-exhaustive-start-start-exhaustive-contact-details-reveal-full/llms.txt)

## Fiber AI's APIs (9)

- [Fiber AI: email verification API pricing, 9 plans](https://datacircle.dev/validate-email-apis/fiber-ai/free-cardless-api-trial/llms.txt)
- [Fiber AI: LinkedIn company search API pricing, 13 plans](https://datacircle.dev/linkedin-company-search-apis/fiber-ai/free-cardless-api-trial/llms.txt)
- [Fiber AI: LinkedIn people search API pricing, 13 plans](https://datacircle.dev/linkedin-people-search-apis/fiber-ai/free-cardless-api-trial/llms.txt)
- [Fiber AI: LinkedIn job search API pricing, 13 plans](https://datacircle.dev/linkedin-job-search-apis/fiber-ai/free-cardless-api-trial/llms.txt)
- [Fiber AI: reverse email lookup API pricing, 9 plans, POST /v1/email-to-person/single/lite](https://datacircle.dev/reverse-email-lookup-apis/fiber-ai/free-cardless-api-trial-post-v1-email-to-person-single-lite/llms.txt)
- [Fiber AI: reverse email lookup API pricing, 9 plans, POST /v1/email-to-person/single](https://datacircle.dev/reverse-email-lookup-apis/fiber-ai/free-cardless-api-trial-post-v1-email-to-person-single/llms.txt)
- [Fiber AI: email finder API pricing, 9 plans, batch/start, Start batch contact details, full](https://datacircle.dev/find-email-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start-start-batch-contact-details-full/llms.txt)
- [Fiber AI: LinkedIn company data API pricing, 12 plans, POST /v1/kitchen-sink/company](https://datacircle.dev/linkedin-company-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-kitchen-sink-company/llms.txt)
- [Fiber AI: LinkedIn company data API pricing, 12 plans, POST /v1/linkedin-live-fetch/company/single](https://datacircle.dev/linkedin-company-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-linkedin-live-fetch-company-single/llms.txt)
- [Fiber AI: LinkedIn company data API pricing, 12 plans, POST /v1/linkedin-live-fetch/batch/start](https://datacircle.dev/linkedin-company-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-linkedin-live-fetch-batch-start/llms.txt)
- [Fiber AI: LinkedIn profile API pricing, 12 plans, kitchen-sink/person, Kitchen sink person lookup](https://datacircle.dev/linkedin-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-kitchen-sink-person-kitchen-sink-person-lookup/llms.txt)
- [Fiber AI: LinkedIn profile API pricing, 12 plans, kitchen-sink/person, Kitchen sink person lookup with liveFetch](https://datacircle.dev/linkedin-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-kitchen-sink-person/llms.txt)
- [Fiber AI: LinkedIn profile API pricing, 12 plans, linkedin-live-fetch/profile/single](https://datacircle.dev/linkedin-profile-apis/fiber-ai/free-cardless-api-trial/llms.txt)
- [Fiber AI: LinkedIn profile API pricing, 12 plans, linkedin-live-fetch/batch/start](https://datacircle.dev/linkedin-profile-apis/fiber-ai/free-cardless-api-trial-post-v1-linkedin-live-fetch-batch-start/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/premium-phone/sync](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-premium-phone-sync/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/lite](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-lite/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/single](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-single/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/turbo/sync](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-turbo-sync/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/batch/start](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-batch-start/llms.txt)
- [Fiber AI: phone finder API pricing, 9 plans, POST /v1/contact-details/exhaustive/start](https://datacircle.dev/find-phone-apis/fiber-ai/free-cardless-api-trial-post-v1-contact-details-exhaustive-start/llms.txt)

## Fiber AI: email finder API alternatives

- [The Swarm, $1,990 yearly](https://datacircle.dev/find-email-apis/the-swarm/1990-yearly/llms.txt): $66.333 per 1,000, 60% complete, 1 day
- [Pubrio, $2,388 yearly](https://datacircle.dev/find-email-apis/pubrio/2388-yearly/llms.txt): $66.333 per 1,000, 20% complete, stored
- [LeadIQ, $240.24 yearly, Pro, 3,600 credits a year, POST /graphql, searchPeople](https://datacircle.dev/find-email-apis/leadiq/240-24-yearly-pro-3600-credits-a-year-post-graphql-searchpeople/llms.txt): $66.733 per 1,000, 80% complete, 1 month
- [lemlist, $134 pack](https://datacircle.dev/find-email-apis/lemlist/134-pack/llms.txt): $67.00 per 1,000, 60% complete, live

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-10-23.

- https://api.fiber.ai/ai-docs/pollBatchContactDetails.md
- https://api.fiber.ai/ai-docs/startBatchContactDetails.md
- https://api.fiber.ai/llms-full.txt
- https://docs.fiber.ai/billing
- https://docs.fiber.ai/billing/pricing
- https://docs.fiber.ai/build/rate-limits
- https://docs.fiber.ai/enrichment/contact-reveal
- https://docs.fiber.ai/linkedin/live-fetch
- https://www.fiber.ai/llms.txt
- https://www.fiber.ai/pricing
- https://www.fiber.ai/pricing.md
- https://www.fiber.ai/terms