# Free App Development Tools

> Free app development calculators: timeline estimator, tech stack recommender, and cost calculator. Plan your app project with published industry data.

Canonical: https://app369.com/tools/

Interactive calculators and recommenders to help you plan your app project. Get instant estimates for timeline, cost, and technology stack.

**Already know the problem?** The offer finder matches it to a fixed-price offer and shows the price. Seeing an error message instead? [See the error fixes](https://app369.com/fix/).

[**Open the offer finder**](https://app369.com/tools/fixed-price-offer-finder/) [**See all offers**](https://app369.com/fixed-price/)

[🔎<h2>**AI App Security Check**</h2>Paste your live app’s address to find secret keys shipped in its JavaScript, its Supabase or Firebase project, and missing security headers. Passive, nothing stored. Fixed-price help: **AI-Built App Rescue, from $450****Try it free **](https://app369.com/tools/ai-app-check/) [🛡<h2>**Firebase Security Rules Checker**</h2>Paste firestore.rules or storage.rules to find public paths, test-mode rules, sign-in-only checks and ownership takeovers. Runs in your browser. Fixed-price help: **Firebase Security Rules Audit + Fix PR, $950**** Try it free **](https://app369.com/tools/firebase-rules-checker/) [🗝<h2>**Supabase Grants & RLS Checker**</h2>Paste a Supabase migration to find tables that need a GRANT after October 30, RLS that is off, policies of true and views that skip RLS. Runs in your browser. Fixed-price help: **AI-Built App Rescue, from $450**** Try it free **](https://app369.com/tools/supabase-oct-30-checker/) [🔐<h2>**Supabase RLS Policy Checker**</h2>Paste Supabase policy SQL to find policies of true, sign-in-only checks, user_metadata roles, storage buckets anyone can list or write to, and exposed security definer functions. Runs in your browser. Fixed-price help: **AI-Built App Rescue, from $450**** Try it free **](https://app369.com/tools/supabase-rls-policy-checker/) [📅<h2>**Google Play Deadline Checker**</h2>Paste your Android build files to check Google Play’s target API 36, 16 KB page size and Billing Library 8 and 9 deadlines, with the date and fix for each. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/google-play-deadline-checker/) [🔑<h2>**App Handover Checklist**</h2>Switching app developers or agencies? Tick what your app uses (App Store, Google Play, Firebase, Supabase, Stripe, GitHub, Lovable, Bolt, Vercel, domain) and get the ownership steps in order, from each vendor’s own help pages, plus a request to send the outgoing developer. Fixed-price help: **Monthly Dev Subscription, from $1,495/month**** Try it free **](https://app369.com/tools/app-handover-checklist/) [🧭<h2>**Fixed-Price Offer Finder**</h2>Pick what you need (one bug, an AI-built app that breaks, a high Firebase bill, Stripe subscriptions, a new web app) and see which fixed-price offer covers it, with its price.** Try it free **](https://app369.com/tools/fixed-price-offer-finder/) [🔥<h2>**Firebase Shutdown Checker**</h2>Paste your dependency files, firebase.json or server code to find retired Firebase products and APIs, from the legacy FCM send API to Test Lab in 2027, with the date and fix for each. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/firebase-shutdown-checker/) [🔢<h2>**Meta Graph API Version Checker**</h2>Paste your app or server code and dependency files to find the Graph API and Marketing API versions you call, with the Available Until date for each and what happens after it. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/meta-graph-api-version-checker/) [⌚<h2>**Fitbit and Google Fit Shutdown Checker**</h2>Paste your dependency files or code to find calls to the legacy Fitbit Web API, turned off November 2, 2026, and the Google Fit APIs, supported until the end of 2026, with the replacement for each. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/fitbit-google-fit-shutdown-checker/) [⚙️<h2>**Cloud Functions Node.js 20 Runtime Checker**</h2>Paste firebase.json, functions/package.json or deploy commands to see which Cloud Functions runtimes you deploy, with Google’s deprecation and decommission dates. Node.js 20 is decommissioned on October 30, 2026. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/cloud-functions-nodejs-20-runtime-checker/) [🔐<h2>**Auth0 Rules and Hooks to Actions Checker**</h2>Paste your Auth0 Rules, Hooks or Terraform config to see what each line becomes in Actions and what needs rework. Auth0 says Rules and Hooks stop running after November 18, 2026. Runs in your browser. Fixed-price help: **App Fix Ticket, from $450**** Try it free **](https://app369.com/tools/auth0-rules-hooks-to-actions-checker/) [💸<h2>**Min Instances Cost Calculator**</h2>See what minimum instances on Cloud Functions (2nd gen) and Cloud Run cost per month while idle, from Google’s published list prices. Fixed-price help: **Firebase Cost-Cut Audit, $750**** Try it free **](https://app369.com/tools/min-instances-cost-calculator/) [🧮<h2>**Lovable and Bolt Credits Calculator**</h2>Enter the Lovable credits or Bolt tokens you have used on one problem and see what it cost in dollars at your plan’s published rate. Fixed-price help: **AI-Built App Rescue, from $450**** Try it free **](https://app369.com/tools/lovable-bolt-credits-calculator/) [🛒<h2>**Shopify App Script Checker**</h2>Paste your store’s page source to see every third-party script, which ones block rendering, app embeds, and ScriptTag apps, which Shopify stops running on March 1, 2027. Runs in your browser. Fixed-price help: **Shopify Speed & Checkout Tune-Up, $750**** Try it free **](https://app369.com/tools/shopify-app-script-checker/) [⏱️<h2>**App Development Timeline Calculator**</h2>Estimate how long your app project will take based on type, complexity, features, and team size. Get a phase-by-phase breakdown. Fixed-price help: **Web App MVP Sprint, from $6,000**, after a $450 scoping** Try it free **](https://app369.com/tools/app-timeline-calculator/) [🧮<h2>**App Development Cost Calculator**</h2>Get a low-to-high cost range, per-feature breakdown, timeline and yearly maintenance, with every assumption and source listed. Fixed-price help: **Web App MVP Sprint, from $6,000**, after a $450 scoping** Try it free **](https://app369.com/tools/app-cost-calculator/) [⚙️<h2>**Technology Stack Recommender**</h2>Answer questions about your goals, platforms, and requirements to get a personalized technology stack recommendation. Fixed-price help: **Web App MVP Sprint, from $6,000**, after a $450 scoping** Try it free **](https://app369.com/tools/tech-stack-recommender/) [💰<h2>**App Cost Estimate Creator**</h2>Get an instant custom estimate for your app development project based on platform, features, timeline, and budget.** Try it free **](https://app369.com/instant-quote/)

## **Ready to get it fixed? **

Every fixed-price offer has a written scope and a fixed price, and the work happens in writing with no call needed. The offer finder matches your problem to one.

[**Open the offer finder**](https://app369.com/tools/fixed-price-offer-finder/) [**See all fixed-price offers**](https://app369.com/fixed-price/)

Have a question first? Email [simon@app369.com](mailto:simon@app369.com?subject=Question%20about%20a%20fixed-price%20offer), and Simon replies by email, usually within one business day.