# USACallerLookup, free: Phone validation API

> USACallerLookup offers a free, read-only JSON API over our phone number and robocall complaint data. No API key, no signup, no cost.

USACallerLookup's Free plan for the phone validation API costs $0.00 per 1,000 phones. We check each provider's docs for 9 fields. USACallerLookup's docs list 4: Formats, Validity, Carrier, Place.
USACallerLookup limits how many calls you get but gives no number.
In [our phone validation API benchmark](https://datacircle.dev/best-phone-validation-api.txt), this plan scores 0.0 out of 100. USACallerLookup ranks 61st of 66 providers.
We rank 1,494 plans for phone validation APIs by price. Half the plans cost $3.20 or less per 1,000 phones. This plan and 20 others tie for the lowest price per 1,000 phones of the 1,494 plans. [326 phone validation API plans on our price sheet are free.](https://datacircle.dev/best-phone-validation-api.txt) [Trestle](https://datacircle.dev/validate-phone-apis/trestle/free/llms.txt) has a free plan with 25 calls in total. Trestle is the best phone validation API in our benchmark.
[Trestle](https://datacircle.dev/validate-phone-apis/trestle/top-up-from-10-self-serve-pay-as-you-go-get-3-0-phone-intel-phone-validation-api/llms.txt), [Signal House](https://datacircle.dev/validate-phone-apis/signal-house/top-up-from-10/llms.txt) and [Data247](https://datacircle.dev/validate-phone-apis/data247/12-pack-membership-get-v3-0-verify247-phone/llms.txt) are the best phone validation API providers in the Datacircle benchmark.

- This page: https://datacircle.dev/validate-phone-apis/usacallerlookup/free
- [Phone validation API in 2026: the best of 60+ compared](https://datacircle.dev/best-phone-validation-api.txt)
- Get it: https://www.usacallerlookup.com/api/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=phone-validation-api-pricing
- Request: `GET https://www.usacallerlookup.com/wp-json/ucl/v1/number/{phone}`
- API key: not needed
- Its API docs: https://www.usacallerlookup.com/api/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=phone-validation-api-pricing
- Sold by: USACallerLookup (https://www.usacallerlookup.com?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=phone-validation-api-pricing)
- Checked: 2026-11-10

## In the answer

- Completeness: 44%
- Formats: ✓
- Validity: ✓
- Carrier: ✓
- Place: ✓

## Score

- Overall score: 0.0. We give it 0 overall because its Accuracy score is 0.
- Price score: 100
- Accuracy score: 0
- Cost to get started score: 100
- Bundle score: 0
- Performance score: 0. We could not measure how fast this provider answers a call, so we count it as 0.

## Price

- $ per 1,000 phones: $0.00
- Per: call
- Billing: free

## Aggregators

- Aggregators: none

## Charges

- Also pays for: nothing else

## Not found

- $ per 1,000 calls that find nothing: $0.00

## In their words

- Their pitch: USACallerLookup offers a free, read-only JSON API over our phone number and robocall complaint data. No API key, no signup, no cost.

## Data

- Freshness: 1 day
- Countries: United States
- What it checks: numbering plan
- Keep data: no limit
- Use data: "Use it in apps, research, call-blocking tools, or anything else." The data is "dedicated to the public domain under CC0" [...] "this API must not be used to determine eligibility for credit, employment, housing, or any other FCRA-regulated purpose."

## Plan

- Pay: $0

## Rate limit

- Per second: 1
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: phone
- Method: GET
- Path: /wp-json/ucl/v1/number/{phone}

## About the plan

- Plan: Free
- Who can get it: anyone

## The 16 fields the plan's answer can hold

formatted phone number, normalized phone number, toll-free, city, state, carrier, total complaints, robocall complaints, first seen, last seen, states reporting, complaint subject, complaints per subject, community reports, details URL, attribution

## USACallerLookup's plans (1)

- [USACallerLookup, free](https://datacircle.dev/validate-phone-apis/usacallerlookup/free/llms.txt): $0.00 per 1,000, 44% complete, 1 day

## USACallerLookup's calls (1)

- `GET /wp-json/ucl/v1/number/{phone}`: [USACallerLookup, free](https://datacircle.dev/validate-phone-apis/usacallerlookup/free/llms.txt)

## USACallerLookup's APIs (1)

- [USACallerLookup Phone validation API pricing, 1 plan](https://datacircle.dev/validate-phone-apis/usacallerlookup/free/llms.txt)

## USACallerLookup: phone validation API alternatives

[USACallerLookup alternatives: every phone validation API provider ranked](https://datacircle.dev/usacallerlookup-alternatives.txt)

We list other providers' plans closest to this plan in price per 1,000 phones. Each plan in the list gives live data or data at most a day old.

- [Signal House, free](https://datacircle.dev/validate-phone-apis/signal-house/free/llms.txt): $0.00 per 1,000, 44% complete, live
- [Abstract API, free](https://datacircle.dev/validate-phone-apis/abstract-api/free/llms.txt): $0.00 per 1,000, 89% complete, 1 day
- [Foxentry, free trial, POST /phone/validate, Validate phone number (extended)](https://datacircle.dev/validate-phone-apis/foxentry/free-trial-post-phone-validate-validate-phone-number-extended/llms.txt): $0.00 per 1,000, 56% complete, live
- [HLR Lookups, free, 100 free lookups, POST /hlr-lookups](https://datacircle.dev/validate-phone-apis/hlr-lookups/free-100-free-lookups-post-hlr-lookups/llms.txt): $0.00 per 1,000, 56% 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 2026-11-10.

- https://www.usacallerlookup.com/api/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=phone-validation-api-pricing
- https://www.usacallerlookup.com/wp-content/uploads/api/openapi.json?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=phone-validation-api-pricing