This document explains how to configure each social login provider (Google, Facebook, LinkedIn, Naver, Kakao, LINE) in the Simple Easy Social Login (SESLP) plugin.

All sign-ins are based on OAuth 2.0 / OpenID Connect (OIDC).
You must create an app (client) in each provider’s console and enter the Client ID / Client Secret in SESLP.

πŸ”§ Common Setup Guide

1) Redirect URI rule:

https://{your-domain}/?social_login={provider}

Examples:

2) HTTPS required.

Most providers require HTTPS and will reject http:// redirects.

3) Exact matching

The Redirect URI in the console must match 100% with what SESLP sends (protocol, subdomain, path, trailing slash, and query string).

4) Email may be unavailable

Some providers allow users to deny email sharing. SESLP can fall back to stable provider IDs to link accounts.

5) Where to check logs

🐞 Debug Log & Troubleshooting

How to read SESLP debug logs

Log file location

  • /wp-content/SESLP-debug.log (SESLP debug log)
  • /wp-content/debug.log (WP_DEBUG_LOG = true)

Log format

[YYYY-MM-DD HH:MM:SS Z] [LEVEL] Message {"key":"value",...}
  • Z: UTC or WordPress local time (e.g. KST) β€” selectable in SESLP Settings
  • Privacy: Emails/tokens/secrets are masked automatically (example: r********@g****.com)

OAuth flow logs (common)

1) OAuth start

[DEBUG] State created {"provider":"google","state":"906****23","ttl":"10min"}

Meaning: CSRF protection state token created. ttl is valid for 10 minutes.

2) Callback triggered

[DEBUG] Auth route triggered {"provider":"google","has_code":1}

Meaning: Callback entered. has_code:1 β†’ OAuth code received.

3) State validation

Success:

[DEBUG] State validated {"provider":"google","state":"906****23"}

Failure:

[WARNING] State validation failed: not found/expired {"provider":"google","state":"906****23"}

4) Token exchange

[DEBUG] Token response (google) {"has_access_token":1}

Meaning: Token obtained.

Failure:

[ERROR] Token request failed (google) {"error":"..."}

5) Userinfo request

[ERROR] Userinfo request failed (google)
[WARNING] Invalid userinfo (google)

6) User linker

[DEBUG] Linker: signing in user {"user_id":45,"provider":"google","created":0}
[INFO]  Login success (google) {"user_id":45,"email":"r********@g****.com"}

7) Redirect

[DEBUG] Redirect decision {"mode":"profile","user_id":45,"url":"https://example.com/wp-admin/profile.php"}

Quick reference table

Log Message (short) Likely Cause Action
State validation failed Timeout, tab switch, duplicate request Retry quickly, use private mode
Token request failed Wrong client ID/secret/redirect, blocked request Check dev console, firewall, server time
Userinfo invalid Missing scope or email private Add email, profile scope, user consent
User create failed Account conflict or WordPress restriction Check existing users, multisite rules
Redirect missing Early return in code Ensure Redirect class runs after callback

Helpful info to include in bug reports

  • Relevant log lines (masked)
  • Provider used (Google/Naver/etc.)
  • Redirect mode/custom URL
  • Debug logging state
  • WordPress environment (single site, multisite, cache plugins)

🌍 Provider Guides

Expand each provider below and paste the English guide content you’ve prepared for that provider.

Google
  • Recommended scopes: openid email profile
  • Redirect URI rule: https://{domain}/?social_login=google

1) Preparation (Mandatory Checklist)

(1) HTTPS recommended/essential (Use trusted development certificates for local environments).

(2) Redirect URI must exactly match 100% the value registered in the console. Ex) https://example.com/?social_login=google

(3) In test mode, only test users can log in (up to 100 users).

(4) When using app homepage/privacy policy/terms URLs, app domains (Authorized domains) registration and ownership verification may be required.

2) Project/Consent Screen Setup

(1) Access Google Cloud Console.
https://console.cloud.google.com/apis/credentials

(2) Select project at top β†’ Create new project (if needed).

(3) Sidebar: go to APIs & Services β†’ OAuth consent screen.

(4) Select User Type: usually External.

(5) Enter App Information: App name, user support email, (optional) logo.

(6) App domain section

  • Enter app homepage URL, privacy policy URL, terms of service URL
  • Add root domain (e.g., example.com) to Authorized domains β†’ Save
  • If needed, perform domain ownership verification via Search Console.

(7) Configure Scopes

  • Recommended: openid, email, profile
  • Sensitive/restricted scopes may require review before going live.

(8) Add Test users (emails allowed to log in in test mode).

(9) Save.

Note: Using only the basic scopes (openid email profile) often allows operation (publishing) without review.

3) Create OAuth Client (Web Application)

(1) Sidebar: APIs & Services β†’ Credentials.

(2) Top: + Create Credentials β†’ OAuth client ID.

(3) Application type: Web application.

(4) Enter a distinguishable Name (e.g., SESLP – Front).

(5) Add Authorized redirect URIs

  • https://{domain}/?social_login=google

(6) Click Create, then copy the displayed Client ID / Client Secret.

(Optional) Authorized JavaScript origins are usually unnecessary for this plugin using code grant.

4) WordPress (Plugin) Setup

(1) WP Admin β†’ SESLP Settings β†’ Google tab.

(2) Paste Client ID / Client Secret β†’ Save.

(3) Test with the Google login button on the site frontend.

5) Switch from Test to Production

(1) Check OAuth consent screen β†’ Publishing status.

(2) To switch from test to production:

  • Verify app info (logo/app domain/policies/terms) is accurate.
  • Remove unnecessary scopes, keep only needed scopes.
  • Submit review request if using sensitive scopes.

(3) After switching to production, all Google accounts can log in.

6) Common Errors & Solutions

(1) redirect_uri_mismatch

β†’ Occurs if the Redirect URI registered in the console and the actual request URI differ even slightly (including protocol, subdomain, slash, query). Fix to match exactly.

(2) access_denied / disallowed_useragent

β†’ Browser/in-app environment restrictions. Retry in a regular browser.

(3) invalid_client / unauthorized_client

β†’ Client ID/Secret typo or app status (deleted/disabled). Reissue/recheck credentials.

(4) Email is empty

β†’ Check if email scope is included, consent screen exposure, and account email visibility/security settings. Clearly explain email permission usage in the consent screen.

Check logs:

  • wp-content/SESLP-debug.log (plugin debug ON)
  • wp-content/debug.log (WP_DEBUG, WP_DEBUG_LOG = true)

7) Summary Checklist

  • OAuth consent screen: set app info/domain/policies/terms/scopes/test users
  • Credentials: create Web Application client
  • Register Redirect URI: https://{domain}/?social_login=google
  • SESLP: save Client ID/Secret and test login
  • Change publishing status when going live (submit review if needed)
Facebook
  • Redirect URI: https://{domain}/?social_login=facebook
  • Requested Permissions (Recommended): public_profile, email
  • Facebook does not use openid.

1) Create App and Add Product

(1) Go to Meta for Developers β†’ Log in
https://developers.facebook.com/

(2) Click Create App β†’ Select a general type (e.g., Consumer) β†’ Create app

(3) In the left sidebar, add Facebook Login from Products

(4) Go to Settings β†’ Check the following items:

  • Client OAuth Login: ON
  • Web OAuth Login: ON
  • Valid OAuth Redirect URIs:
  • Add https://{domain}/?social_login=facebook
  • (Optional) Enforce HTTPS: Recommended by default

2) Basic App Settings (App Settings β†’ Basic)

(1) App Domains: example.com (the domain of the app’s policy/terms/homepage URL)

(2) Privacy Policy URL: Publicly accessible policy page

(3) Terms of Service URL: Publicly accessible terms page

(4) User Data Deletion: Provide a guideline URL or a data deletion endpoint

(5) Category / App Icon: Set appropriately, then Save

3) Scopes (Permissions) and App Review

(1) The basic permissions required for standard login are public_profile; the optional email is email

(2) In most cases, email can be used without review, but there may be exceptions depending on region/account

(3) Advanced permissions such as for pages/ads require App Review and Business Verification

4) Switch Mode (Development β†’ Live)

At the top or in the app settings area, switch App Mode: Development β†’ Live

5) Checklist before switching to Live

  • Prepare Privacy Policy / Terms / Data Deletion URL
  • Enter Valid OAuth Redirect URIs accurately
  • Remove unnecessary permissions, request only required ones
  • (If needed) Complete App Review/Business Verification

6) WordPress Settings (SESLP)

(1) WP Admin β†’ SESLP Settings β†’ Facebook

(2) Enter App ID / App Secret β†’ Save

(3) Test with the Facebook login button on the frontend

7) Troubleshooting

(1) Can't Load URL / redirect_uri error

β†’ Make sure the exact same URI is registered in Valid OAuth Redirect URIs (including protocol, subdomain, slash, query string)

(2) email null

β†’ The user has not registered an email with Facebook or it is private. Prepare ID-based account linking logic, and clearly explain the email permission usage in the consent screen

(3) Permission-related errors

β†’ If the requested scope exceeds the basic range, App Review/Business Verification is required

(4) Cannot switch to Live

β†’ If the policy/terms/data deletion guideline URL is missing or not public. You must provide a public URL

LinkedIn
  • Redirect URI: https://{domain}/?social_login=linkedin
  • Required Setting: Enable OpenID Connect (OIDC)
  • Recommended Scopes: openid, profile, email
  • LinkedIn is phasing out legacy scopes (r_liteprofile, r_emailaddress).
  • New apps must use OIDC standard scopes.

1) Create an Application

(1) Go to LinkedIn Developers Console

β†’ https://www.linkedin.com/developers/apps

(2) Log in with LinkedIn account

(3) Click Create app

(4) Fill in required fields:

  • App name: e.g., MySite LinkedIn Login
  • LinkedIn Page: Select or β€œNone”
  • App logo: 100Γ—100+ PNG/JPG
  • Privacy Policy URL / Business Email: Valid and public

(5) Click Create app

Development Mode by default β†’ immediate testing of openid, profile, email login without publishing

2) Enable OpenID Connect (OIDC)

(1) Go to Products tab

(2) Find Sign In with LinkedIn using OpenID Connect

(3) Click Add product β†’ Approved instantly

(4) OIDC settings appear in Auth tab

OIDC Scopes Required

  • openid β†’ ID token
  • profile β†’ Name, photo, headline
  • email β†’ Email address

3) OAuth 2.0 Settings (Auth Tab)

(1) Navigate to Auth β†’ OAuth 2.0 settings

(2) Add to Redirect URLs:

β†’ https://{domain}/?social_login=linkedin

(3) Exact match required (protocol, subdomain, slash, query)

(4) Register multiple if needed:

  • Local: https://localhost:3000/?social_login=linkedin
  • Staging: https://staging.example.com/?social_login=linkedin
  • Production: https://example.com/?social_login=linkedin

(5) Click Save

4) Get Client ID / Client Secret

(1) In Auth tab, find:

  • Client ID
  • Client Secret

(2) WordPress Admin β†’ SESLP Settings β†’ LinkedIn

(3) Paste both β†’ Save

(4) Test with LinkedIn login button on frontend

Security:

  • Never expose Client Secret
  • Use Regenerate secret if compromised

5) Scopes Explained

Scope Description Note
openid Returns OIDC standard ID token Required
profile Name, photo, headline, etc. Required
email Email address Required

Legacy scopes (r_liteprofile, r_emailaddress)

  • Deprecated after 2024
  • Not available for new apps

6) Troubleshooting

(1) redirect_uri_mismatch

β†’ URIs differ even slightly β†’ ensure 100% match

(2) invalid_client

β†’ Wrong ID/Secret or app inactive β†’ recheck or regenerate

(3) email NULL

β†’ User denied or email scope missing β†’ explain usage in consent screen

(4) insufficient_scope

β†’ Requested scope not approved β†’ verify OIDC enabled

(5) OIDC not enabled

β†’ Missing Sign In with LinkedIn using OpenID Connect in Products

Logs:

  • /wp-content/SESLP-debug.log
  • /wp-content/debug.log

7) Summary Checklist

  • App created
  • OpenID Connect product added
  • Redirect URI registered exactly
  • Client ID/Secret saved in SESLP
  • Scopes: openid profile email (no legacy scopes)
  • Tested on HTTPS frontend

Note:

  • SESLP fully supports OIDC flow.
  • Legacy OAuth 2.0 is no longer supported.
  • Always use OpenID Connect for new integrations.
Naver
  • Redirect URI: https://{domain}/?social_login=naver
  • Recommended Scopes: Basic Profile (name), Email (email)
  • Naver uses Naver Login (λ„€μ•„λ‘œ) API, HTTPS required

1) Application Registration

(1) Go to Naver Developer Center

β†’ https://developers.naver.com/apps/

(2) Log in with Naver account

(3) Click Application β†’ Register Application

(4) Fill in required fields:

  • Application Name: e.g., MySite Naver Login
  • API Usage: Select Naver Login (λ„€μ•„λ‘œ)
  • Add Environment β†’ Web
  • Service URL: https://example.com
  • Callback URL: https://example.com/?social_login=naver

(5) Agree to terms β†’ Register

Note:

  • HTTPS mandatory β†’ HTTP not allowed
  • Subdomains must be registered separately

2) Get Client ID / Client Secret

(1) Go to My Applications

(2) Click the app β†’ copy Client ID and Client Secret

3) WordPress (Plugin) Settings

(1) WP Admin β†’ SESLP Settings β†’ Naver

(2) Paste Client ID / Client Secret

(3) Ensure Redirect URI matches exactly: https://{domain}/?social_login=naver

(4) Save β†’ Test with Naver login button on frontend

4) Permissions and Data Provision

Data Scope Note
Name name Default
Email email Default
Gender, Birthday Separate Review required
  • Users can agree/decline on consent screen
  • If email declined β†’ email = null β†’ use ID-based linking
  • Sensitive data requires Naver app review

5) Troubleshooting

(1) Redirect URI mismatch

β†’ Even slight difference β†’ ensure 100% match

(2) HTTP error

β†’ Must use HTTPS

(3) Subdomain error

β†’ Register each subdomain separately

(4) email NULL

β†’ User declined or private β†’ prepare ID-based logic

(5) Review needed

β†’ Basic login: no review
β†’ Additional data: review required

Logs:

  • /wp-content/SESLP-debug.log
  • /wp-content/debug.log

6) Summary Checklist

  • App registered in Naver Developer Center
  • Callback URL registered exactly
  • HTTPS used
  • Subdomains registered separately (if needed)
  • Client ID/Secret saved in SESLP
  • Tested email agree/decline behavior
  • Frontend login test completed

Note:

  • SESLP fully supports Naver Login (λ„€μ•„λ‘œ).
  • Basic login (name, email) is available without review.
Kakao
  • Redirect URI: https://{domain}/?social_login=kakao
  • Recommended Scopes: profile_nickname, profile_image, account_email
  • account_email available only after identity or business verification
  • HTTPS required, Client Secret activation mandatory

1) Create Application

(1) Go to Kakao Developers

β†’ https://developers.kakao.com/

(2) Log in β†’ My Applications β†’ Add New App

(3) Enter:

  • App Name, Company Name
  • Category
  • Agree to Operation Policy

(4) Save

2) Enable Kakao Login

(1) Product Settings > Kakao Login

(2) Toggle Enable Kakao Login β†’ ON

(3) Register Redirect URI

  • https://{domain}/?social_login=kakao
  • Save

(4) Domain must match Platform site domain

3) Consent Items (Scopes)

(1) Consent Items

(2) Add and configure:

Scope Description Consent Type Note
profile_nickname Nickname Required/Optional Basic
profile_image Profile Image Required/Optional Basic
account_email Email Optional Verification required

(3) Clearly state purpose for each

(4) Save

Note: Sensitive scopes require verification

4) Register Web Platform

(1) App Settings > Platform

(2) Register Web Platform

(3) Site Domain: https://{domain}

(4) Save β†’ Must match Redirect URI domain

5) Security – Generate & Activate Client Secret

(1) Product Settings > Security

(2) Use Client Secret β†’ ON

(3) Generate Secret β†’ Copy value

(4) Activation Status β†’ Active

(5) Save

Important: Must activate after generation

6) Get REST API Key (Client ID)

(1) App Keys

(2) Copy REST API Key β†’ Use as Client ID

7) WordPress Settings

(1) WP Admin β†’ SESLP Settings β†’ Kakao

(2) Client ID = REST API Key
Client Secret = Generated Secret

(3) Save

(4) Test with Kakao Login Button

8) Troubleshooting

(1) redirect_uri_mismatch β†’ 100% match required

(2) invalid_client β†’ Secret not activated or typo

(3) email empty β†’ User declined or unverified

(4) Domain mismatch β†’ Platform vs Redirect URI

(5) HTTP forbidden β†’ HTTPS only

Logs:

  • /wp-content/SESLP-debug.log
  • /wp-content/debug.log

9) Summary Checklist

  • Kakao Login enabled
  • Redirect URI registered
  • Web platform domain registered
  • Consent items configured
  • Client Secret generated + activated
  • REST API Key / Secret in SESLP
  • Tested on HTTPS frontend
LINE
  • Redirect URI: https://{domain}/?social_login=line
  • Required: Enable OpenID Connect, Apply & get approved for Email permission
  • Recommended Scopes: openid, profile, email
  • HTTPS mandatory, Email permission requires approval

1) Create Provider and Channel

(1) Access LINE Developers Console

β†’ https://developers.line.biz/console/

(2) Log in with LINE Business Account (personal account not allowed)

(3) Click Create a new provider β†’ Enter name β†’ Create

(4) Under the provider β†’ Channels tab

(5) Select Create a LINE Login channel

(6) Configure:

  • Channel type: LINE Login
  • Provider: Select created provider
  • Region: Target country (e.g., South Korea, Japan)
  • Name / description / icon: Shown on consent screen

(7) Agree to terms β†’ Create

2) Enable OpenID Connect & Apply for Email Permission

(1) Go to OpenID Connect in left menu

(2) Click Apply next to Email address permission

(3) Fill out application:

  • Privacy Policy URL (must be publicly accessible)
  • Upload screenshot of Privacy Policy
  • Submit

(4) email scope works only after approval
β†’ Approval usually takes 1–3 business days

3) Register Callback URL & Publish Channel

(1) Go to LINE Login in left menu

(2) Enter Callback URL:

β†’ https://{domain}/?social_login=line

(3) Exact match required:

  • Protocol: https:// (HTTP not allowed)
  • Domain, path, query string must 100% match

(4) Click Save

(5) Change channel status to Published

  • Development mode: test only
  • Published: live service

4) Get Channel ID / Secret

(1) Channel top or Basic settings

(2) Channel ID β†’ SESLP Client ID
Channel Secret β†’ SESLP Client Secret

5) WordPress Settings

(1) WP Admin β†’ SESLP Settings β†’ LINE

(2) Client ID ← Channel ID
Client Secret ← Channel Secret

(3) Save

(4) Test with LINE login button on frontend

6) Troubleshooting

(1) redirect_uri_mismatch β†’ Even slight difference causes error β†’ 100% match

(2) invalid_client β†’ Secret typo or not Published

(3) email NULL β†’ Email permission not approved or user declined

(4) HTTP not allowed β†’ HTTPS required (localhost HTTPS OK)

(5) Development mode limit β†’ Only test accounts can log in

Logs:

  • /wp-content/SESLP-debug.log
  • /wp-content/debug.log

7) Summary Checklist

  • Created Provider + LINE Login channel with Business Account
  • Email permission applied and approved
  • Callback URL registered exactly
  • HTTPS used, Published status
  • Channel ID/Secret β†’ SESLP saved
  • Frontend login test completed

Note: SESLP fully supports

  • LINE Login v2.1 + OpenID Connect.
  • Email collection requires pre-approval.