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Fixed-price offerGet a bug in your mobile or web app fixed, at a fixed price

A build that won’t compile, a login loop, a database write that never finishes, a webhook that fails. Flutter, Swift, Kotlin, React or Vue on the front, Firebase or Node.js behind it. Send the repo and the steps to reproduce it; you get the root cause with evidence, then a fix delivered as a pull request with a test that keeps it fixed.

Pay $450 for a DiagnosisPay $1,200 for a Fix

Full refund if Simon can’t take it on once he sees your project, or if you cancel before work starts.

Check fit by email

Not sure what causes the bug? Start with the Diagnosis. Already know the cause? Pay for the Fix.

Resubmit before Apple’s holiday slowdown

Pay for the Diagnosis and send the rejection and access to the app by (US Eastern). The Diagnosis is back by . Pay for the Fix that day and it arrives as a pull request by , in time to build and resubmit before .

In past years Apple said reviews may take longer around the holidays: December 20 to 26 in 2024 (opens in a new tab), December 22 to 27 in 2023 (opens in a new tab), December 23 to 27 in 2022 (opens in a new tab). Apple hasn’t posted its 2026 dates yet (checked ). Approval stays Apple’s decision.

Diagnosis $450 in 3 business days, credited toward the fix. Fix $1,200 in 5 business days. Counted from repo access and reproduction steps.

Price checked .

No call needed. Ask a question first by email at contact@app369.com or with the contact form; we reply by email, usually within one business day.

Short answer

The App Fix Ticket handles one reproducible bug in an existing Flutter, Swift, Kotlin, React, Vue, Firebase or Node.js app. A $450 Diagnosis finds the root cause in 3 business days and is credited toward the fix. The Fix for one scoped defect, a tested pull request, is $1,200 in 5 business days.

App Fix Ticket

One reproducible issue in an existing mobile or web app, diagnosed and fixed at a fixed price. Flutter, Swift, Kotlin, React, Vue, Firebase or Node.js.

Diagnosis

$450
3 business days

The root cause with evidence, plus a fixed repair quote. The $450 is credited toward the fix.

Pay $450 for a Diagnosis

Full refund if Simon can’t take it on once he sees your project, or if you cancel before work starts.

Fix

$1,200
5 business days

One scoped defect fixed, delivered as a pull request with a regression test and handover notes.

Pay $1,200 for a Fix

Full refund if Simon can’t take it on once he sees your project, or if you cancel before work starts.

Typical issues

  • Build failures
  • Auth and login loops
  • Database writes that hang
  • API, webhook or Cloud Function errors
  • A broken screen

Delivery

Diagnosis in 3 business days, Fix in 5 business days, counted from repo access and reproduction steps.

After you pay

Simon emails you within one business day to confirm and send the access checklist. You can also send it straight away to contact@app369.com. What the work needs:

  • Access to the repository (GitHub, GitLab or Bitbucket)
  • Exact steps to reproduce the bug: build, device and OS, account, taps, expected and actual result
  • Any error messages, logs or a screen recording

Diagnosis: Delivery takes 3 business days from repo access and reproduction steps.

Fix: Delivery takes 5 business days from repo access and reproduction steps.

Full refund if Simon can’t take it on once he sees your project, or if you cancel before work starts.

Not sure it fits? See who it fits, or email a question about this offer; we reply by email, usually within one business day.

This fits when

  • One bug has already cost you more than a day
  • iOS or Android builds fail after a Flutter, Xcode or Gradle upgrade
  • Users land back on the sign-in screen, or the app flickers between screens
  • Firestore writes hang, or an API or Cloud Function only returns an error
  • A screen goes red in debug or grey in release

Errors this fixes

Each page explains the error from the vendor’s own docs, with what to try first.

See every error fix

How it works

  1. Pay and send the repo

    Pay for the Diagnosis or, if you already know the cause, the Fix. Reply to the Stripe receipt with repo access and the exact steps to reproduce the bug.

  2. Reproduce and isolate

    The bug is reproduced on the build and device class you name, then isolated to the app, the backend or the build tooling, using local emulators where they apply. Your production data is never touched.

  3. Root cause and a fixed quote

    The Diagnosis ends with the root cause, the evidence for it and a fixed repair quote. If you go ahead, the $450 is credited.

  4. Fix as a pull request

    The Fix arrives as a pull request with a regression test and handover notes. You review and merge it.

What a Diagnosis looks like

The findings table from a sample Diagnosis of an example Flutter shop app whose Play Store update won’t go through. It is the example built into the free Google Play deadline checker, run on October 23, 2026, so you can reproduce every line yourself.

  1. Target API is 34, Google Play needs 36

    Evidence
    android/app/build.gradle: targetSdkVersion 34
    Google’s date
    August 31, 2026 (extension to November 1, 2026)
    What the fix changes
    targetSdk 36 and compileSdk at least 36, then test edge-to-edge, back gestures and tablets

  2. Play Billing Library 7.0.0 is below 8

    Evidence
    android/app/build.gradle: billing-ktx:7.0.0
    Google’s date
    August 31, 2026 (extension to November 1, 2026)
    What the fix changes
    Billing Library 8 or later; going straight to 9 saves a second update before August 31, 2027

  3. Android Gradle Plugin 8.1.0 is below 8.5.1

    Evidence
    android/build.gradle: com.android.tools.build:gradle:8.1.0
    Google’s date
    February 1, 2027 (16 KB page sizes)
    What the fix changes
    AGP 8.5.1 or higher

  4. NDK r26 needs linker flags

    Evidence
    android/app/build.gradle: ndkVersion "26.1.10909125"
    Google’s date
    February 1, 2027 (16 KB page sizes)
    What the fix changes
    NDK r28 or higher, or the 16 KB linker flags

Sample only: an example app, not a client’s project. A real Diagnosis also reproduces the problem on your build, names the root cause with its evidence, and ends with a fixed quote for the repair, with the $450 credited if you go ahead.

Run the same check on your Gradle files

Questions before you pay

What if I already know what’s wrong?
Is it only for Flutter apps?
Do you work on FlutterFlow or other generated code?
Can you guarantee App Store or Play approval?
Do I need a call before I pay?
Who owns what you deliver?

Fiverr reviews / 95 on app work

What buyers said about this kind of work

Read 126 of the 127 reviews
  • “Very good work on the design. Looking forward to working with Szymon on the app development! Highly recommend!”
    Eric, United States, June 2021. App design on Fiverr
  • “Szymon explained to me in detail the steps of the project. I appreciate his honesty and patience in explaining his service to someone like me who does not understand most technical lingo. I highly recommend his service!”
    A buyer in the United States, May 2021. App development on Fiverr
  • “Amazing work! I love working with Szymon. He is proactive, intelligent, and creative! If you need any app development, you should definitely shoot him a message! The whole process was spectacular!”
    Mark, United States, May 2021. App development on Fiverr

Read the whole story

Ready to start?

Pay online and send what the work needs by replying to the Stripe receipt. Simon, who builds and runs the SaaS Workspace369, does the work himself.

Pay $450 for a DiagnosisPay $1,200 for a Fix

Full refund if Simon can’t take it on once he sees your project, or if you cancel before work starts.

Further reading

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