Google Trends caveat: It's a lagging indicator — people search after seeing the price move, not before. Still useful as a retail temperature gauge, but don't expect it to front-run price.
Free/open-source APIs worth looking at:
https://alternative.me/crypto/fear-and-greed-index/ — free REST API, updated daily, composite of volatility, momentum, social volume, dominance, and trends
mempool.space API — for on-chain fee pressure as a proxy for demand
Blockchain.com stats API — free historical data for active addresses, transaction volume
On-chain metrics that tend to lead sentiment:
MVRV ratio (market value vs. realized value) — spikes above ~3.5 have historically aligned with tops; free data from LookIntoBitcoin
Funding rates on perpetual futures — available from most exchanges' public APIs; extreme positive funding often precedes corrections
One thing I'd watch for in backtests: sentiment-weighted DCA can underperform in prolonged bear markets because sentiment stays low for extended periods, causing you to over-invest into a continuing decline. Worth stress-testing against 2018 and 2022 specifically.
On the data sources question specifically:
Google Trends caveat: It's a lagging indicator — people search after seeing the price move, not before. Still useful as a retail temperature gauge, but don't expect it to front-run price.
Free/open-source APIs worth looking at:
On-chain metrics that tend to lead sentiment:
One thing I'd watch for in backtests: sentiment-weighted DCA can underperform in prolonged bear markets because sentiment stays low for extended periods, causing you to over-invest into a continuing decline. Worth stress-testing against 2018 and 2022 specifically.