# GenderAPI.io vs Genderize.io

> Compare GenderAPI.io V2 and Genderize.io: name inputs, batch limits, authentication, confidence fields, unknown results and the work needed to switch integrations.

Canonical HTML: https://www.genderapi.io/genderapi-io-vs-genderize-io

Last reviewed: 2026-09-26

## About this comparison

Published by GenderAPI.io, one of the providers discussed. This is a dated review of public documentation, not an independent performance test or an endorsement by another provider. We did not run competitor prediction requests. Undocumented in a reviewed reference does not mean unavailable. Recheck the linked contract and pricing before integrating.

## What changes between these APIs?

Genderize documents a compact name-focused GET interface. GenderAPI.io V2 combines names, emails and usernames in one request model with explicit AI modes. Choose by your input workflow and evidence requirements; this comparison does not identify an accuracy winner.

| Decision point | GenderAPI.io V2 | Genderize.io | Sources |
| --- | --- | --- | --- |
| Inputs and country | Names, email addresses and usernames use type and value on /api/v2/gender. Optional country supplies context. | First or full name via name; country_id adds country context. Dedicated email and username inputs are not documented in this reference. | [GenderAPI.io V2 request parameters](https://www.genderapi.io/docs/v2/request-parameters); [Gender API reference](https://genderize.io/documentation/api/reference) |
| Authentication | Authorization: Bearer with a GenderAPI.io key. Query keys are available for simple GET examples; prefer headers in applications. | apikey in the query string of GET https://api.genderize.io. | [GenderAPI.io V2 authentication](https://www.genderapi.io/docs/v2/authentication); [Gender API reference](https://genderize.io/documentation/api/reference) |
| Batch requests | Up to 50 keyed items or 10 IP-trial items. Each item can have its own type, country and options. | Repeated name[] parameters; up to 100 names with one country_id. | [GenderAPI.io V2 batch guide](https://www.genderapi.io/docs/v2/batch); [Gender API reference](https://genderize.io/documentation/api/reference) |
| Confidence and unknowns | data.confidence is 0–1 or null. confidence_kind distinguishes stored-count frequency from an AI score; sample_count is null for AI. data.result_status: unknown; data.gender and data.confidence are JSON null. Inspect data.reason. | gender may be null. probability is 0–1; count reports evidence count. | [GenderAPI.io V2 responses](https://www.genderapi.io/docs/v2/responses); [Gender API reference](https://genderize.io/documentation/api/reference) |
| AI routing | Explicit off, fallback or always. Singles default to fallback; batches default to off. Optional forceToGenderize uses the dataset first, then nickname-aware AI. | Request-level AI controls are not documented in the reviewed reference. | [GenderAPI.io V2 AI options](https://www.genderapi.io/docs/v2/ai-options); [Gender API reference](https://genderize.io/documentation/api/reference) |
| Usage accounting | Ordinary successful lookups cost 1 credit, even unknowns and fallback AI. Always-AI costs 2. forceToGenderize costs 1 for a resolved dataset result or 2 when AI runs. | Plans count each name, including names within a batch. Monthly allowances reset. | [GenderAPI.io V2 credits and usage](https://www.genderapi.io/docs/v2/credits-and-usage); [Pricing and plans for Genderize.io](https://genderize.io/pricing) |

## Before you switch an integration

Change the URL, credential and request parser together. Map name to type: name plus value, and country_id to country. Read data.gender instead of a top-level gender field. Split 100-name batches to the V2 limit. Select options.ai_mode explicitly so switching providers does not silently enable a different inference path.

Even where probability and confidence share a 0–1 scale, their evidence and thresholds are not interchangeable. Preserve unknowns and inspect confidence_kind before using a score in application logic.

Sources: [Gender API reference](https://genderize.io/documentation/api/reference); [GenderAPI.io V2 request parameters](https://www.genderapi.io/docs/v2/request-parameters); [GenderAPI.io V2 responses](https://www.genderapi.io/docs/v2/responses); [GenderAPI.io V2 AI options](https://www.genderapi.io/docs/v2/ai-options); [GenderAPI.io V2 batch guide](https://www.genderapi.io/docs/v2/batch)

- [V2 request fields](https://www.genderapi.io/docs/v2/request-parameters)
- [V2 response fields](https://www.genderapi.io/docs/v2/responses)
- [Batch processing and item errors](https://www.genderapi.io/docs/v2/batch)

## Evaluate the workflow you will deploy

Choose a representative sample you are permitted to process and keep the original inputs, preprocessing and country context fixed. Evaluate name, email and username workflows separately. Record provider, endpoint, date, configuration and whether AI was used.

Measure coverage (answered / eligible), accuracy among answered results (correct / answered), and correct results across all eligible inputs (correct / eligible). Report unknowns, errors, costs and latency separately. A threshold should be selected on validation data and then checked on a held-out sample.

GenderAPI.io does not publish an independent reference-labelled accuracy benchmark here. Database counts, contract tests and one provider's published study cannot establish which service will work best on your data. An inferred association does not establish a person's gender identity.

Sources: [GenderAPI.io accuracy methodology](https://www.genderapi.io/accuracy-methodology)

- [Our methodology and current evidence limits](https://www.genderapi.io/accuracy-methodology)
- [Dated database profile](https://www.genderapi.io/data-provenance)

## Does this comparison show which API is more accurate?

No. Genderize publishes provider-run evaluations, but this review did not rerun them or test GenderAPI.io V2 on the same labelled sample. Use those studies as methodological evidence, not a cross-provider ranking.

Sources: [How Accurate Is Genderize? Open Benchmarks](https://genderize.io/our-data); [GenderAPI.io accuracy methodology](https://www.genderapi.io/accuracy-methodology)

## Can I reuse my Genderize key with GenderAPI.io?

No. These are separate services with separate accounts. Use your GenderAPI.io key and verify meta.access.mode is api_key; missing or unrecognized keys can fall back to the shared IP trial.

Sources: [GenderAPI.io V2 authentication](https://www.genderapi.io/docs/v2/authentication)

## Sources and review date

- [GenderAPI.io V2 request parameters](https://www.genderapi.io/docs/v2/request-parameters): Reviewed 2026-09-26
- [GenderAPI.io V2 authentication](https://www.genderapi.io/docs/v2/authentication): Reviewed 2026-09-26
- [GenderAPI.io V2 responses](https://www.genderapi.io/docs/v2/responses): Reviewed 2026-09-26
- [GenderAPI.io V2 AI options](https://www.genderapi.io/docs/v2/ai-options): Reviewed 2026-09-26
- [GenderAPI.io V2 batch guide](https://www.genderapi.io/docs/v2/batch): Reviewed 2026-09-26
- [GenderAPI.io V2 credits and usage](https://www.genderapi.io/docs/v2/credits-and-usage): Reviewed 2026-09-26
- [GenderAPI.io accuracy methodology](https://www.genderapi.io/accuracy-methodology): Reviewed 2026-09-26
- [GenderAPI.io pricing](https://www.genderapi.io/price): Reviewed 2026-09-26
- [How Accurate Is Genderize? Open Benchmarks](https://genderize.io/our-data): Reviewed 2026-09-26
- [Pricing and plans for Genderize.io](https://genderize.io/pricing): Reviewed 2026-09-26
- [Gender API reference](https://genderize.io/documentation/api/reference): Reviewed 2026-09-26