Fix Firebase Phone Auth "Not Authorized" Error (Backend Access Only)

@abhishekchouras6

As an experienced mobile app developer with a focus on Android, I have a proven track record of troubleshooting intricate backend issues similar to yours with Firebase and GCP. My expertise aligns closely with the requirements you've laid out, from auditing fingerprints and reviewing API restrictions to ensuring the backend handshake is correctly wired between Firebase Auth and the Cloud project. Using my deep understanding of FlutterFlow's connections with Firebase, I'm confident we can resolve this phone auth issue without you needing to share your editor access. We'll address the "Not Authorized" message users are encountering, while protecting the integrity of other enabled auth methods and Firebase services. My commitment to meeting deadlines and delivering high-quality work accompanied by a comprehensive summary of all implemented changes for future reference make me the ideal candidate for this project. Let's connect and navigate through these Firebase intricacies together, ensuring that your FlutterFlow app's phone sign-in process is flawless and seamless.

@buttphool6991

As a seasoned Full-Stack Developer with a decade of experience, I specialize in creating secure and scalable digital solutions by implementing the perfect mix of front-end and back-end technologies. My proficiency with Flutter, Android, and extensive knowledge of Firebase and Google Cloud make me equipped to tackle the specific problem you're experiencing with your phone authentication on your FlutterFlow app. I've audited the SHA-1 / SHA-256 fingerprints for several apps, verified their validity, and addressed any ensuing issues successfully. In addition, Identity Toolkit API restrictions that could interfere with the phone auth endpoint won't pose a challenge as I'm very conversant with API troubleshooting. I've also extensively worked with OAuth consent screen settings and know how to ensure valid Authorized Domains - all to ensure there are no authorization hiccups. You can expect not just a resolution but also a future-proof solution as I stay current with latest technology trends. Let me help you eliminate this "Not Authorized" issue while boosting your confidence in the reliability of your app's backend. Sharpen your competitive edge by hiring me!

@fd3os

Hi there, I can resolve this for you. The 'Not Authorized' error on Firebase Phone Auth is almost always caused by one of three things: missing or mismatched SHA fingerprints, a blocked Identity Toolkit API in the GCP console, or an unlisted domain in the Authorized Domains list. My exact approach (without FlutterFlow access): Audit all SHA-1/SHA-256 fingerprints registered in your Firebase project and cross-check them against GCP. Navigate to GCP APIs & Services and verify that the Identity Toolkit API is enabled and unrestricted for your app's API key. Check Firebase Auth → Settings → Authorized Domains to ensure all relevant domains are whitelisted. Review the OAuth consent screen and confirm the Firebase-GCP service account linkage is intact. I will document every change made with before/after screenshots so you have a clean audit trail. Estimated turnaround: within a few hours of receiving Firebase and GCP access. Ready to start immediately. Best regards

@elite14

i am mern satck web developer with 3yrs+ of experience i can be good fit for this....i have experience with firebase a lot,...

@guptakishan805

Hello, I have 5+ years of experience working with Firebase Authentication and Google Cloud, resolving complex authorization issues including phone auth failures and Identity Toolkit misconfigurations. I’ve handled SHA key mismatches, API restrictions, OAuth setup, and project linkage issues across multiple production apps. My approach is a structured audit of Firebase Auth, GCP IAM, API restrictions, SHA fingerprints, and authorized domains, followed by precise fixes without impacting existing services. I ensure a clean validation flow with test builds and provide a clear summary of all changes made. I’m confident in resolving this quickly and reliably. Let’s connect and fix your phone authentication issue end-to-end.

@christianrainer4

Hi, there. My name is Christian. I am familiar with Firebase, especially in Firebase Authentication. I guess your flutterflow project have some configuration mistakes. If you are fine, I am going to solve them in remote session on your mac so that you can solve issues without sharing full access of Flutterflow project. Thanks so much. Christian Sassmann

@kanchansharma05

Hi, I can help you fix the “Not Authorized” issue with Phone Authentication in your FlutterFlow app without needing access to the FlutterFlow editor. I’ve handled similar Firebase Auth issues before, especially around misconfigured SHA keys, API restrictions, and Identity Toolkit errors. I have around 4+ years of experience working with Flutter, Firebase, and Node/Firebase backends, and I’m comfortable working directly in Firebase Console and Google Cloud (IAM) to debug and resolve this properly. How I’ll approach this: Audit and fix SHA-1 / SHA-256 fingerprints for Android builds Check and correct Identity Toolkit API restrictions and key settings Verify Authorized Domains & OAuth consent configuration Ensure proper Firebase ↔ GCP linkage (common cause of “Not Authorized”) Test the full phone auth flow using your provided build What you’ll get: Working phone number login (no “Not Authorized” error) No impact on other Firebase services Clear summary of what was wrong and what I fixed I can start immediately and should be able to resolve this within a few hours to 1 day, depending on the current setup. Let’s fix this quickly ? Thanks, Kanchan Sharma

@aniket202005

Proposal: Firebase & GCP Phone Auth Resolution ​The "Not Authorized" error in FlutterFlow is a classic handshake failure between the Identity Toolkit API and your app's signing credentials. I will resolve this entirely via Firebase and GCP. ​?️ Resolution Strategy ​Fingerprint Audit: I will verify that the SHA-1 and SHA-256 fingerprints in Firebase match your production and debug keystores, ensuring they are whitelisted in GCP Credentials. ​API Restriction Fix: I will audit your Google Cloud API keys to ensure the Identity Toolkit API is explicitly allowed and not blocked by restrictive settings. ​OAuth & Domain Validation: I will confirm that the OAuth 2.0 Client IDs are valid and that your Authorized Domains are correctly configured in Firebase Auth. ​Backend Handshake: I will check for quota hits or billing issues in the Google Cloud Library that might trigger unauthorized responses. ​⏱️ Timeline & Access ​Diagnosis: 1–2 hours after access. ​Implementation: 1 hour. ​Turnaround: Same-day delivery (3–5 hours total). ​Access Required: Project Editor role for Firebase Console and Google Cloud Platform. ​✅ Acceptance Criteria ​Successful phone sign-in on your test build. ​Zero disruption to other Firebase services. ​A summary report of all backend modifications. ​I am ready to start immediately. Let's fix your authentication flow.

@MaysaraNassar202

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@ttobio69

Dear Client, I have read all your requirements carefully, and I understand that users in your FlutterFlow app are getting a “Not Authorized” error during phone sign-in, and that you need this resolved strictly through Firebase Console and the linked Google Cloud project without access to the FlutterFlow editor. I have already worked on several similar Firebase and Google Cloud integration issues before, including Firebase Authentication setup, SHA fingerprint configuration, API restriction fixes, authorized domain checks, and backend auth troubleshooting. With over 5 years of experience in this field, I am confident I can identify the root cause and fix it cleanly without affecting your other Firebase services. My approach will be to audit the registered SHA-1 and SHA-256 fingerprints, review Identity Toolkit and related API restrictions, verify Authorized Domains and OAuth settings, and confirm the Firebase Auth and GCP project linkage is configured correctly. I will make sure phone authentication works properly on your test build while keeping the rest of your auth methods and services stable. I can finish the project within your required timeline, and I would be happy to discuss the cost in detail based on the exact scope of work. Best regards, Oluwatobi Okedairo

@CodeByYousuf

Hi, I have reviewed your requirements, and I can help you troubleshoot and resolve the “Not Authorized” issue in your FlutterFlow app related specifically to Firebase Phone Authentication. I have worked on several Firebase and GCP-based projects where I handled authentication issues, API configuration, and project-level security settings. I am comfortable working directly in Firebase Console and Google Cloud IAM to diagnose and fix issues like this without affecting other services. For your project, I will: * Audit SHA-1 and SHA-256 fingerprints in Firebase and Google Cloud * Review Firebase Authentication settings, especially Phone Auth configuration * Check and fix API restrictions (including Identity Toolkit and related services) * Verify authorized domains and OAuth consent screen configuration * Ensure Firebase Auth is properly linked with the Google Cloud project backend * Test and confirm that the phone authentication flow works correctly I will make sure the fix is isolated to the authentication issue only and does not impact any other Firebase services in your project. Acceptance Criteria: 1. Phone number sign-in works successfully in your test build 2. No disruption to existing Firebase services or authentication methods 3. A clear summary report of all changes and fixes applied I can start immediately and aim to resolve this as quickly as possible once access is provided. Looking forward to working with you. Best regards, Yousuf

@vinodrayka07

Hi, I can resolve the “Not Authorized” issue in your FlutterFlow app’s Phone Authentication directly from Firebase and Google Cloud without needing FlutterFlow access. Approach: • Audit and update SHA-1 / SHA-256 fingerprints in Firebase & GCP • Review Identity Toolkit API restrictions and ensure proper access • Verify Authorized Domains and OAuth consent configuration • Check Firebase ↔ GCP linkage to fix auth handshake issues • Test end-to-end phone sign-in on your provided build I will ensure no other Firebase services or auth methods are impacted during the fix. Deliverables: ✔ Fully working phone number sign-in ✔ Clean and stable configuration ✔ Summary of all changes made for future reference I’ve handled similar Firebase auth issues before and can quickly identify misconfigurations. Estimated turnaround: 1 day Let’s get this fixed efficiently.

@kratika0510

Being a passionate web developer, I understand the vital importance of smooth user experiences and uninterrupted service. I have extensive experience working with APIs and integrating them seamlessly into existing systems. With expertise in projects encompassing Java, Mobile App Development and most importantly, Flutter, I'm confident in rectifying your Firebase Phone Authentication error. Although I might not be proficient in using FlutterFlow, I assure you that I can navigate around your Firebase and Google Cloud settings to conduct the necessary audits and make the recommended corrections. My knowledge extends beyond simple coding tasks—I focus on the bigger picture. In line with this project's requirements, I will review API restrictions (Identity Toolkit), verify Authorized Domains and OAuth consent screen settings, and ensure backend handshakes between Firebase Auth and GCP are properly set to eliminate that persistent "Not Authorized" response. My goal is for phone number sign-ins to complete smoothly without any disruption to other authentication methods or Firebase services. Providing a brief yet detailed summary of all actions taken is standard practice for me; I always ensure future reference is available for clients. My approach would minimize reliance on FlutterFlow access while effectively resolving the issue at hand. Rest assured, Kratika is here to help streamline your app authentication process!

@GouravW1

Hi, Your title says it all — and this is exactly the kind of fix I specialize in. "Not Authorized" on Firebase Phone Auth with backend-only access points to one of three things: SHA-1/SHA-256 fingerprints missing or mismatched in Firebase Identity Toolkit API disabled or blocked by GCP key restrictions Phone Auth provider misconfigured at the Firebase Console level I'll get in, find it, fix it, and get out — no FlutterFlow editor needed. What's included: SHA fingerprint audit and correction (debug + release) GCP API key restriction review — Identity Toolkit confirmed reachable Phone Auth provider and Authorized Domains verified Firebase ↔ GCP backend linkage confirmed Written changelog of every single thing I touched What I won't do: touch any other auth method, Firestore rules, or unrelated config — clean, surgical fix only. Delivery: Same day, typically within 2–4 hours of access Price: Rs. 1300 fixed — no surprises To start immediately I need Firebase Console editor access and GCP IAM editor access. If you have device logs or an error code handy (even a screenshot), share it and I can likely pinpoint the exact cause before I even log in. Ready when you are.

@zenstro

Hi! I can help resolve the “Not Authorized” issue with your phone authentication. I’ll audit your Firebase and Google Cloud setup—checking SHA fingerprints, API restrictions (especially Identity Toolkit), authorized domains, OAuth settings, and the Firebase–GCP linkage—to pinpoint and fix the problem without needing FlutterFlow access. Once done, I’ll verify phone sign-in on your test build and ensure no other services are affected. I’ll also provide a clear summary of all changes made. Estimated turnaround: 1–2 days depending on access. Let me know when you can grant access, and I’ll get started right away.

@Ashoksahu001

hello, I have built and scaled numerous websites, mobile apps, and even custom software systems like the one you're seeking help with. My expertise includes the backend development work you need for this project. For Flutter projects, I am more than familiar with Firebase and its suite of services - Phone Authentication being no exception. I understand how frustrating it can be for users to encounter errors during sign-in, but rest assured my skills extend to resolving these exact issues efficiently. Through my ample experience across different technologies, I've developed a knack for troubleshooting APIs and ensuring correct setup between different platforms - essentially what you need done in this project. Moreover, prioritizing a seamless user experience while making necessary improvements is something I value greatly. Thank you for considering my bid. Should you have any questions or require further information, please do not hesitate to reach out.

@madhusudhanan047

Hi, Thank you for the detailed explanation of the issue. Based on your description, the “Not Authorized” error in phone authentication is typically related to configuration issues between Firebase Authentication and Google Cloud (such as SHA keys, API restrictions, or Identity Toolkit settings). I can audit and fix the following: • Verify and update SHA-1 / SHA-256 fingerprints • Review API restrictions and ensure Identity Toolkit access • Check authorized domains and OAuth settings • Validate Firebase ↔ Google Cloud integration I will ensure phone sign-in works correctly on your test build without affecting other services, and I’ll provide a clear summary of all changes made. Estimated time: 4-5 days Looking forward to working with you. Thank you!

@DKDEV2001

Hello, I can fix the “Not Authorized” issue in your Phone Authentication directly via Firebase and Google Cloud—no FlutterFlow access needed. After recent FlutterFlow updates, many apps are facing SHA fingerprint issues—I’ve already fixed this for similar cases. I’ll: * Verify and correct SHA-1/SHA-256 fingerprints * Fix Identity Toolkit/API restrictions * Check authorized domains & OAuth settings * Ensure proper Firebase ↔ GCP integration **Result:** Phone sign-in working on your test build without affecting other services, plus a summary of changes. Timeline: 1 day after access Needed: Firebase + FF Access Ready to start immediately. Best regards, Deepak Kumar

@erdavinder2307

Hi, This “Not Authorized” issue in Firebase Phone Auth is usually caused by misconfigured SHA fingerprints, restricted Identity Toolkit API, or mismatched project settings between Firebase and GCP. I can quickly audit your Firebase and Google Cloud setup, verify SHA-1/SHA-256 keys, check API restrictions, authorized domains, and ensure the authentication handshake is correctly configured. I’ve worked with Firebase Auth and similar issues before, so I can resolve this without needing FlutterFlow access. Expected turnaround: a few hours after access is granted. Quick question: Is this issue happening on all devices or only specific builds (debug/release)? I’ll also provide a clear summary of changes made so you can track everything. Ready to start immediately.