| Element | Description | |---------|-------------| | Hero | Large tagline: “Download videos instantly – any format, any device.” CTA: Get Started (opens modal). | | URL Input Card | Centered box with placeholder “Paste video URL here…”. After paste → auto‑detect thumbnail + “Fetch options” button. | | Feature Grid | 4 columns: Fast, Batch, Premium, Secure – each with icon & short blurb. | | Pricing | Simple toggle: Free vs Pro – compare features side‑by‑side. | | Footer | Links: Terms, Privacy, DMCA, Contact, Social icons. |
| ID | As a … | I want … | So that … |
|----|--------|----------|-----------|
| US‑001 | Casual Viewer | One‑click “Download” button after pasting a video URL | I can get the file instantly without extra steps. |
| US‑002 | Casual Viewer | A preview of available resolutions/formats before download | I can pick the right size for my device. |
| US‑003 | Content Creator | “Batch Download” where I upload a CSV/JSON list of URLs | I can download dozens of videos in one go. |
| US‑004 | Educator | Option to include subtitles or closed captions in the output file | My students can follow along in any language. |
| US‑005 | Power User | RESTful API with API‑key authentication to request downloads programmatically | I can integrate SXEY into my own pipelines. |
| US‑006 | Compliance Officer | Detailed download logs (timestamp, IP, user ID, video ID, chosen format) stored for 90 days | I can audit usage for policy compliance. |
| US‑007 | All Users | Transparent “Legal Use” check that warns if the video is likely copyrighted and requires user confirmation. | I stay within legal bounds and the platform avoids liability. |
| US‑008 | All Users | “Premium” tier that removes rate‑limits, adds 4K+ downloads, and offers a download‑accelerator (parallel chunking). | I get faster, higher‑quality downloads when I pay. |
| US‑009 | All Users | Dark‑mode UI and responsive design for mobile browsers. | Comfortable viewing on any device, day or night. |
| US‑010 | Power User | CLI tool (sxey-dl) that wraps the API for local batch jobs. | I can run automated jobs without opening a browser. |
| # | Requirement | Priority | Acceptance Criteria |
|---|-------------|----------|---------------------|
| FR‑1 | URL Input & Validation – Accept YouTube, Vimeo, Dailymotion, Facebook, Instagram, TikTok, and user‑uploaded MP4 links. | Must | - Invalid URLs show a clear error.
- Supported URLs show a “✓” and a preview thumbnail. |
| FR‑2 | Resolution/Format Picker – Populate list based on source capabilities (e.g., 144p‑8K, MP4/WEBM, audio‑only MP3/AAC). | Must | - List updates in < 500 ms after URL validation.
- Pre‑select “best‑compatible” (720p MP4) for free users. |
| FR‑3 | One‑Click Download – Trigger server‑side fetch, transcoding (if needed), and delivery via secure temporary link (expires in 10 min). | Must | - Download begins within 2 s of click.
- Link is HTTPS and uses a signed token. |
| FR‑4 | Batch Processor – Accept up to 100 URLs per request (CSV/JSON). Process in parallel with max 4 concurrent jobs per user (adjustable for premium). | Should | - Returns a zip file with all requested videos.
- Provides per‑item status (success/failure) in a JSON manifest. |
| FR‑5 | Subtitle Integration – Detect embedded or external subtitles (SRT, VTT) and optionally mux them into the output file. | Should | - A toggle “Include subtitles” appears when subtitles exist.
- Output file contains subtitles track. |
| FR‑6 | API Endpoint – POST /api/v1/download with JSON payload url, format, subtitles, api_key. Returns signed URL or job ID. | Must | - Rate‑limited (free: 20 req/min; premium: 200 req/min).
- Proper error codes (400, 401, 429, 500). |
| FR‑7 | CLI Wrapper – sxey-dl (Node/Python) that reads a file of URLs, calls the API, and saves files locally. | Should | - Works on Windows/macOS/Linux.
- Shows progress bars per video. |
| FR‑8 | Legal‑Use Guard – Run a quick “copyright‑risk” check (e.g., based on video metadata, content‑ID flags) and display a modal requiring user acknowledgment before proceeding. | Must | - Modal appears for “high‑risk” videos.
- User can abort or proceed with explicit “I have the right”. |
| FR‑9 | User Account System – Email‑based sign‑up, OAuth (Google, Apple), 2FA optional. Store API keys, download history, and tier status. | Must | - Users can view/download history (last 30 days). |
| FR‑10 | Payment Integration – Stripe (or local alternatives) for subscription plans (Free, Pro $9.99/mo, Enterprise $49.99/mo). | Must | - Successful payment upgrades tier instantly.
- Billing portal for cancellations. |
| FR‑11 | Analytics Dashboard – Real‑time metrics: active users, downloads per hour, average latency, error rate. | Should | - Admin UI shows graphs; data exported as CSV. |
| FR‑12 | Security – All traffic HTTPS, CSRF protection, rate limiting, IP‑based abuse detection, GDPR‑compliant data storage. | Must | - Pen‑test passes OWASP Top‑10.
- No plain‑text passwords stored. |
| FR‑13 | Performance Optimisation – Use edge CDN for static assets, keep‑alive connections, chunked streaming for large files (> 1 GB). | Should | - 95 % of downloads < 5 s for ≤ 720p on a 20 Mbps connection. |
| FR‑14 | Responsive UI – Mobile‑first layout, progressive‑enhancement, accessible (WCAG 2.1 AA). | Must | - All core functions usable via keyboard/touch.
- Color contrast ≥ 4.5:1. |
| FR‑15 | Dark Mode – Automatic based on system preference, toggleable. | Nice‑to‑have | - All UI elements adapt without flicker. |
| Element | Description | |---------|-------------| | Hero | Large tagline: “Download videos instantly – any format, any device.” CTA: Get Started (opens modal). | | URL Input Card | Centered box with placeholder “Paste video URL here…”. After paste → auto‑detect thumbnail + “Fetch options” button. | | Feature Grid | 4 columns: Fast, Batch, Premium, Secure – each with icon & short blurb. | | Pricing | Simple toggle: Free vs Pro – compare features side‑by‑side. | | Footer | Links: Terms, Privacy, DMCA, Contact, Social icons. |
| ID | As a … | I want … | So that … |
|----|--------|----------|-----------|
| US‑001 | Casual Viewer | One‑click “Download” button after pasting a video URL | I can get the file instantly without extra steps. |
| US‑002 | Casual Viewer | A preview of available resolutions/formats before download | I can pick the right size for my device. |
| US‑003 | Content Creator | “Batch Download” where I upload a CSV/JSON list of URLs | I can download dozens of videos in one go. |
| US‑004 | Educator | Option to include subtitles or closed captions in the output file | My students can follow along in any language. |
| US‑005 | Power User | RESTful API with API‑key authentication to request downloads programmatically | I can integrate SXEY into my own pipelines. |
| US‑006 | Compliance Officer | Detailed download logs (timestamp, IP, user ID, video ID, chosen format) stored for 90 days | I can audit usage for policy compliance. |
| US‑007 | All Users | Transparent “Legal Use” check that warns if the video is likely copyrighted and requires user confirmation. | I stay within legal bounds and the platform avoids liability. |
| US‑008 | All Users | “Premium” tier that removes rate‑limits, adds 4K+ downloads, and offers a download‑accelerator (parallel chunking). | I get faster, higher‑quality downloads when I pay. |
| US‑009 | All Users | Dark‑mode UI and responsive design for mobile browsers. | Comfortable viewing on any device, day or night. |
| US‑010 | Power User | CLI tool (sxey-dl) that wraps the API for local batch jobs. | I can run automated jobs without opening a browser. | www sxey video download better com
| # | Requirement | Priority | Acceptance Criteria |
|---|-------------|----------|---------------------|
| FR‑1 | URL Input & Validation – Accept YouTube, Vimeo, Dailymotion, Facebook, Instagram, TikTok, and user‑uploaded MP4 links. | Must | - Invalid URLs show a clear error.
- Supported URLs show a “✓” and a preview thumbnail. |
| FR‑2 | Resolution/Format Picker – Populate list based on source capabilities (e.g., 144p‑8K, MP4/WEBM, audio‑only MP3/AAC). | Must | - List updates in < 500 ms after URL validation.
- Pre‑select “best‑compatible” (720p MP4) for free users. |
| FR‑3 | One‑Click Download – Trigger server‑side fetch, transcoding (if needed), and delivery via secure temporary link (expires in 10 min). | Must | - Download begins within 2 s of click.
- Link is HTTPS and uses a signed token. |
| FR‑4 | Batch Processor – Accept up to 100 URLs per request (CSV/JSON). Process in parallel with max 4 concurrent jobs per user (adjustable for premium). | Should | - Returns a zip file with all requested videos.
- Provides per‑item status (success/failure) in a JSON manifest. |
| FR‑5 | Subtitle Integration – Detect embedded or external subtitles (SRT, VTT) and optionally mux them into the output file. | Should | - A toggle “Include subtitles” appears when subtitles exist.
- Output file contains subtitles track. |
| FR‑6 | API Endpoint – POST /api/v1/download with JSON payload url, format, subtitles, api_key. Returns signed URL or job ID. | Must | - Rate‑limited (free: 20 req/min; premium: 200 req/min).
- Proper error codes (400, 401, 429, 500). |
| FR‑7 | CLI Wrapper – sxey-dl (Node/Python) that reads a file of URLs, calls the API, and saves files locally. | Should | - Works on Windows/macOS/Linux.
- Shows progress bars per video. |
| FR‑8 | Legal‑Use Guard – Run a quick “copyright‑risk” check (e.g., based on video metadata, content‑ID flags) and display a modal requiring user acknowledgment before proceeding. | Must | - Modal appears for “high‑risk” videos.
- User can abort or proceed with explicit “I have the right”. |
| FR‑9 | User Account System – Email‑based sign‑up, OAuth (Google, Apple), 2FA optional. Store API keys, download history, and tier status. | Must | - Users can view/download history (last 30 days). |
| FR‑10 | Payment Integration – Stripe (or local alternatives) for subscription plans (Free, Pro $9.99/mo, Enterprise $49.99/mo). | Must | - Successful payment upgrades tier instantly.
- Billing portal for cancellations. |
| FR‑11 | Analytics Dashboard – Real‑time metrics: active users, downloads per hour, average latency, error rate. | Should | - Admin UI shows graphs; data exported as CSV. |
| FR‑12 | Security – All traffic HTTPS, CSRF protection, rate limiting, IP‑based abuse detection, GDPR‑compliant data storage. | Must | - Pen‑test passes OWASP Top‑10.
- No plain‑text passwords stored. |
| FR‑13 | Performance Optimisation – Use edge CDN for static assets, keep‑alive connections, chunked streaming for large files (> 1 GB). | Should | - 95 % of downloads < 5 s for ≤ 720p on a 20 Mbps connection. |
| FR‑14 | Responsive UI – Mobile‑first layout, progressive‑enhancement, accessible (WCAG 2.1 AA). | Must | - All core functions usable via keyboard/touch.
- Color contrast ≥ 4.5:1. |
| FR‑15 | Dark Mode – Automatic based on system preference, toggleable. | Nice‑to‑have | - All UI elements adapt without flicker. | | Element | Description | |---------|-------------| | Hero