Platforms
Pine Script
Pine Script is TradingView's own programming language for writing custom indicators and strategies that run on TradingView charts.
Pine Script is the language TradingView provides for custom indicators and strategies. Scripts are written in the Pine Editor and run on TradingView's servers, not on your computer. That is why the same indicator works on the website, the desktop app and the mobile app without any installation.
A Pine script runs once on every historical bar, from the oldest to the newest, and then on each update of the live bar. An indicator script plots lines, labels and shapes and can raise alerts. A strategy script also simulates orders, which the Strategy Tester turns into a back-test report. The language is versioned, and the version is declared at the top of the script.
Published scripts come in three kinds. Open-source scripts show their code to everyone. Protected scripts can be added by anyone but the code is hidden. Invite-only scripts have hidden code and work only for TradingView usernames the author has granted access to. Paid indicators are normally invite-only.
For Indian traders the appeal is that TradingView needs no Windows PC and no separate data vendor setup. The limits are TradingView's own: how many indicators per chart, how many alerts, and whether a symbol's data is real-time all depend on your TradingView plan.
The common mistake is trusting a script that repaints. Code that pulls higher-timeframe data carelessly, or acts on the live bar before it closes, shows signals in history that did not exist at the time. Check by watching a script live and comparing with the chart after a reload.
Worked example
How invite-only access works
Illustrative case. Your TradingView username is trader_sk. The author adds it to the script's access list. The script then appears in the Indicators window under Invite-only scripts, on every device where you are logged in. You add it to a 15-minute Bank Nifty chart near 56,000 and it plots like any indicator. You cannot open the source code. Under a different username the script is not there.
In WizeBuySell
The TradingView version of WizeBuySell is an invite-only Pine indicator. We grant access to your TradingView username; nothing is installed. It works on the free TradingView tier, on web, desktop and the mobile app, and plots the same signals: entry, T1, T2, T3 and a trailing stop-loss, confirmed on candle close. The source code is not visible, and TradingView's own alert limits apply to your account.