Bitcoin Fair Value — As the name says, this indicator shows whether current Bitcoin prices are over- or undervalued. It is calculated based on the network value to transaction ratio (NVT) and on-chain data. Terminal.bytetree.com also offers other free Bitcoin indicators and stats. For example, how many Bitcoins are held by funds.
Bitcoin Fear & Green Index — An indicator to check market sentiment for Bitcoin (also applicable for crypto in general).
Bitcoin’s Never Look Back Price — An interactive chart that shows the last time Bitcoin was at a particular price level. Once it reached that price, it only proceeded up and never retraced to that value again.
Bitcoin’s Power Law Corridor — Bitcoin’s Power Law Corridor is the channel within which Bitcoin has been growing in price since its inception, when charted on log price over square-root time scales. Also interactive.
Bollinger Bands — A Bollinger Band includes 3 lines: a simple moving average, a positive, and a negative standard deviation (SD). The closer the price moves to the upper SD line, the more overbought a market. The closer the prices move to the lower SD line, the more oversold the market. On tradingview.com you can use this indicator on different cryptocurrencies.
Combined Orderbook — Coinlobster.com offers a live combined order book across 10 spot and perpetual futures exchanges. The website also has other free features such as liquidation watch and whale watching.
Exchange Reserves — A chart showing the total number of coins held in exchanges. A lower count means that more people are holding their coins in wallets which indicates a lower selling pressure — and vice versa. On cryptoquant.com you can access this chart for several major cryptocurrencies.
Market Value to Realized Value Ratio (MVRV) — Another oversold (MVRV < 1) overbought (MVRV > 3.5) indicator for Bitcoin. On coinmetrics you can use this free indicator on a couple of large cap cryptocurrencies.
Relative Strenght Index (RSI) — Great indicator showing whether Bitcoin is oversold (RSI < 30) or overbought (RSI > 70).