IELTSzy: IELTS Speaking & Prep

IELTS candidates typically juggle multiple apps, static PDFs, and expensive tutors to cover all four skills. Writing and Speaking feedback from human examiners takes days—by which time learners lose momentum without correcting critical mistakes.

Furthermore, finding serious, reliable speaking partners for live IELTS mock interviews across global time zones remained a major hurdle. Candidates needed an integrated platform that pairs instant, examiner-grade AI diagnostics with real-time human speaking practice without video camera pressure.

IELTSzy brings everything into a unified platform:

• **Live Audio-Only Speaking Calls** — Instant peer matching worldwide with synchronized Cambridge cue cards, timed preparation, and voice memos.
• **AI Speaking Examiner** — Diagnostic breakdown across Fluency, Lexical Resource, Grammar, and Pronunciation with actionable tips.
• **AI Writing Evaluator & Band 8+ Rewriter** — Instant Task 1 & 2 evaluation with sentence-level vocabulary upgrades.
• **Exam-Standard CBT Reading & Listening** — Authentic question formats with multi-accent audio and instant explanations.
• **2h 45m Timed Mock Simulations** — Realistic test conditions with predicted Band Score diagnostics.
• **Live on Google Play & Web** — Flutter Android app seamlessly backed by a scalable PHP/MySQL REST API and web platform at ieltszy.com.

Clients
Marketing website · student web app · admin panel (server-rendered) · Flutter app on Google Play (JSON API with Bearer JWT)

Core (app/Core)
Router · Request/Response · PDO with read-replica support · View · Auth with three guards · JWT · Validator · CSRF · RateLimiter · Upload · HTTP client · Cache (Redis, APCu or file) · Queue (database or sync) · Storage (local or S3) · PageCache · database session handler.

Domain services (app/Services)
AiService & AiConfig · PracticeService (grading, streaks, analytics) · MockExamService · BandScore · SpeakingPartnerService · StudyPlanService · TutorService · VocabService (SM-2) · VocabCourseService · SubscriptionService · PaymentFlow & BkashService · NotificationService (FCM v1) · CsvImporter · ExternalAuth (Google / Firebase) · Audit.

Background jobs
EvaluateAttemptJob grades writing and speaking; SendCampaignJob fans out push campaigns. The queue uses SELECT … FOR UPDATE SKIP LOCKED, so any number of workers can run across machines — or a per-minute cron on shared hosting.

CMS
Every website and app section is a typed content block (text, html, tags, images, repeatable lists) with rich defaults; admin overrides merge over them, are cached, and reach the Flutter app through /app/home, /app/features and /onboarding.

Scaling
Guest pages are served from a full-page cache in 1–2 ms with per-request CSRF injection and ETag 304s; sessions and cache move to Redis, files to any S3-compatible store, and heavy reads to a replica — all from .env, no code changes.

• Any number of providers with presets for DeepSeek, Qwen, GLM, Kimi, SiliconFlow, OpenRouter, Gemini, Groq, xAI and OpenAI — any OpenAI-compatible API works. Fetch models loads live model lists and prices; a Test button verifies each one.

• Free and Pro routes per feature — for example free students on an OpenRouter :free model and Pro students on a premium model — each with a primary and an automatic fallback.

• Daily and monthly budgets: at a set threshold every feature switches to its economy model; at 100% it either keeps serving on economy models or pauses AI gracefully.

• Answer cache: an identical submission is served free and scores consistently.

• Per-feature, per-tier control of max output tokens, temperature, chat memory and input length, plus editable instructions with a locked JSON output contract so the apps can never break.

• Cost tracked in USD per call by feature, tier, model and top students, with a 14-day chart, Pro fair-use caps and a per-student daily cap.

AI keys never leave the server.

• Website & App editor — reorder, hide and rewrite every homepage section, menus, skill and AI-tool pages, the onboarding quiz, and the mobile app's banners, tips and feature switches.

• Mock and test builders, plus CSV and whole-course JSON bulk import for tests, writing tasks, speaking questions, vocabulary, flashcards and quizzes — matching items update rather than duplicate.

• Students, submissions, manual bKash payment approval, subscriptions, plans and coupons.

• Push campaigns over FCM with deep links into specific app screens.

• Team roles — Super Admin, Content Editor, Audio Manager, Support and Analytics Viewer — with a full audit log.

• bin/console for key generation, migrations, seeding, admin creation, imports, cron, queue workers and cache clearing; a one-command cPanel packaging script and a step-by-step deployment guide.

• Prepared statements everywhere with whitelisted identifiers.

• CSRF on every web form; HttpOnly, SameSite=Lax session cookies, Secure over HTTPS.

• Short-lived HS256 JWT access tokens and opaque refresh tokens stored hashed and rotated on every refresh.

• Rate limits on login, registration, AI endpoints and payments.

• MIME-checked uploads with random names and PHP execution blocked in uploads; speaking audio deleted after transcription.

• AI, bKash and FCM secrets never reach a device, and account deletion is built in to meet Play Store policy.