Best Open Source Identity Providers (CIAM and SSO) in 2026
A fair comparison of eight open source identity providers for single sign-on and customer login in 2026: Keycloak, Authgear, Authentik, Zitadel, Ory, Authelia, SuperTokens and Logto. Licences, protocols, passkeys, hosting and who each one suits.
Keycloak Custom Login Page: Themes, Limits and Alternatives
How Keycloak themes work in Keycloak 26, a minimal login theme you can deploy as a folder or a JAR, the caching traps that waste an afternoon, and what to re-test at every upgrade.
Keycloak Pricing: What It Really Costs to Run Keycloak
Keycloak is free to download, but not free to run. A simple cost model you can fill in, an illustrative worked example, and how support, Red Hat build of Keycloak, third-party hosting and a vendor-run private cloud change the numbers.
Upgrading Keycloak: What Breaks and How to Plan It
A practical Keycloak upgrade guide for 26.x: how releases work, the official upgrade procedure, database migration, themes and custom providers, rolling updates, a pre-upgrade checklist and a rollback plan.
Keycloak vs Auth0 (and Authgear): Which Should You Choose in 2026?
Keycloak or Auth0? A fair comparison of the open-source identity server and the hosted customer identity platform: licences, hosting, pricing, protocols, customisation, support and data sovereignty, with Authgear as a third option.
Keycloak vs Okta (and Authgear): Self-Hosted vs SaaS Identity
Keycloak or Okta? A fair comparison of the open-source identity server you run yourself and the SaaS identity platform: licences, hosting, pricing, workforce and customer identity, protocols, support and data sovereignty, with Authgear as a third option.
Keycloak vs Zitadel (and Authgear): Open Source Identity Compared
Keycloak and Zitadel are two of the strongest open source identity providers, but they differ on licence, architecture, multi-tenancy and hosting. Here is how they compare in 2026, and where Authgear fits as a third option.
Managed Keycloak vs a Private Cloud: What You Actually Get
The Keycloak project doesn't run a cloud service. Here is what you get from each route instead: running it yourself, a third-party Keycloak host, Red Hat build of Keycloak, or a vendor-run private cloud, compared on upgrades, support, region and exit.
Sovereign Cloud and the CLOUD Act: What They Mean for Login Data
What the US CLOUD Act lets US authorities request, what "sovereign cloud" really means, and the three ways to run your login system if you are in the UK or EU. With a checklist of questions for any auth vendor.
UK Data Sovereignty for Login and Identity Data (2026 Guide)
What UK data sovereignty means for your login system: where user data sits, who runs the system, and whose law applies, from UK GDPR and the Data (Use and Access) Act 2025 to the US CLOUD Act. With a checklist for choosing an auth provider.
2026 年最佳 Twilio 替代方案：SMS 與 OTP 轉換指南
團隊為什麼離開 Twilio、2026 年 SMS 與 OTP 的最佳 Twilio 替代方案（Telnyx、Plivo、Vonage、Sinch、Bird、AWS、Authgear），以及一份轉換時不會讓登入出問題的遷移檢查清單。
2026 最佳 OTP 服務供應商：定價全面比較
2026 年 8 月查證的 10 家 OTP 服務供應商定價：Twilio Verify、Vonage、Plivo、MSG91、Firebase 等。每次驗證實際要花多少錢、哪些需要詢價，以及該如何挑出最適合的一家。
什麼是 SMS sender ID？類型、註冊與取捨
SMS sender ID（寄件者 ID）就是簡訊的「寄件人」欄位：訊息看起來是由哪個名稱或號碼發出。本文介紹各種類型、alphanumeric sender ID 的運作方式、哪些地方需要註冊，以及品牌形象與送達率之間的取捨。
SMS 送達率：為什麼你的簡訊送不到（以及如何解決）
SMS 送達率是指真正抵達手機的簡訊比例。當 OTP 送不到時，登入就會失敗，而且你往往還是得為這次發送付費。以下說明訊息為何會遺失，以及如何提升你的送達率。
什麼是靜默網絡驗證（Silent Network Authentication，SNA）？
靜默網絡驗證透過電信商核實用戶的電話號碼，毋須輸入任何 SMS 驗證碼。本文說明它的運作原理、它在哪些場景勝過 SMS OTP，以及它在哪些情況下仍需要備援方案。
最佳 SMS API 供應商比較（2026）
Twilio、Vonage、Sinch、Bird、Plivo 等：主流 SMS API 供應商在覆蓋範圍、定價與 OTP 支援上的比較，以及該如何選擇，還有 WhatsApp OTP 能在哪些地方省下成本。
什麼是 A2P SMS？（以及它為何是這個價錢）
A2P SMS 是應用程式向用戶發送 OTP、通知和行銷簡訊的方式。這是一個受監管的付費通道，定價方式與個人傳簡訊不同。以下說明 A2P 的意思，以及影響其成本的因素。
什麼是 CPaaS？開發者的通訊 API 指南
CPaaS 讓你透過雲端 API 為應用程式加入 SMS、語音、WhatsApp 和 OTP 驗證，完全不需自行營運電訊基礎設施。本文說明它的運作方式、費用，以及何時該採用。
RCS vs SMS：主要差異、成本，以及 OTP 該用哪一種
RCS 是 SMS 功能更豐富的後繼者：更多元的訊息、已讀回條、加密對話。但對於發送 OTP 來說，成本與觸及率仍然最為關鍵。以下是兩者的比較，以及 WhatsApp 適合切入的位置。
SMS API 定價全解析：每則訊息你實際付多少錢
SMS API 定價不只是每則訊息的費率而已。這篇文章拆解真正推高你 SMS OTP 帳單的因素（目的地費率、電信商附加費、A2P 費用與詐騙），以及如何把它壓下來。
Twilio Verify Pricing & Alternatives (2026)
Twilio Verify charges $0.05 per successful verification on top of channel fees. Here's what it really costs at scale in 2026, when it's worth paying for, and the best alternatives for cutting OTP costs.
WhatsApp API Pricing Explained (2026)
WhatsApp switched to per-message pricing in 2025. Here's how WhatsApp Business API pricing works in 2026 — by message category and country — and what it really costs to send authentication (OTP) messages.
HTTP 401 vs 403: What's the Difference and Which to Return
401 means the server doesn't know who you are; 403 means it knows exactly who you are — and the answer is no. Learn how to fix each error and which one your API should return, with code examples.
MCP Authentication: How OAuth 2.1 Works in the Model Context Protocol
MCP servers expose your data to AI agents — so who checks the agent's ID? A developer's guide to the MCP authorization spec: OAuth 2.1, PKCE, protected resource metadata, and the full flow from 401 to token.