> For the complete documentation index, see [llms.txt](https://docs.developer.singpass.gov.sg/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.developer.singpass.gov.sg/docs/singpass-developer-docs/legacy-myinfo-v3-v4/technical-specifications/myinfo-v4/difference-between-v3-and-v4.md).

# Difference between v3 and v4

The diagram below highlights the end to end flow of v4 APIs with key changes:\
\
![](https://api.singpass.gov.sg/assets/api-lib/myinfo/img/v4/myinfo-v4-flow.png)

Myinfo v4 APIs bring about improved security posture, standards and features.

For the comprehensive list of changes, refer to our [API Specs Release notes](https://public.cloud.myinfo.gov.sg/myinfo/api/myinfo-kyc-v4.0.html).

| v3                            | v4                                                                                                                          | Justification                                                                                                                        |
| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| -                             | Proof of Key Code Exchange (PKCE) (Reference : [PKCE](https://api.singpass.gov.sg/library/myinfo/developers/pkce))          | Improve security posture between /authorize and /token by protecting against authcode injection                                      |
| X.509 Certificate public keys | JSON Web Key Store (JWKS) (Reference : [JWKS](https://api.singpass.gov.sg/library/myinfo/developers/jwks))                  | Enable minimal disruption on key rotations                                                                                           |
| PKI Base string signing       | Client Assertions (Reference : [Client Assertions](https://api.singpass.gov.sg/library/myinfo/developers/clientassertion))  | Alignment to international standards                                                                                                 |
| -                             | Demonstration of Proof-of-Possesion (DPoP) (Reference : [DPoP](https://api.singpass.gov.sg/library/myinfo/developers/dpop)) | Improve security posture between /token and /person by proving legitimacy of possession for access token before data can be released |


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