Free Bollinger Bands API
JSON, Inputs & Python

What a free Bollinger Bands API should provide

A useful technical-indicator API returns Bollinger Bands for a chosen symbol and interval with a documented calculation contract. It should let the application set or verify the moving-average period and standard-deviation multiplier, retrieve timestamped JSON, and connect the result to a chart, scanner, research workflow, or agent without guessing the underlying price series.

Bollinger Bands API inputs and response fields

Reproduce a five-price fixture by hand

Use closing prices 100, 102, 101, 103, 104, a five-period simple moving average, and a multiplier of 2. The middle band is (100+102+101+103+104) ÷ 5 = 102. The squared deviations sum to 10. With population standard deviation (ddof=0), σ is √(10÷5) = 1.4142, so the upper band is 104.8284 and the lower band is 99.1716.

Under the population convention, the last close of 104 gives %B = (104−99.1716) ÷ (104.8284−99.1716) = 0.8536. Bandwidth is (104.8284−99.1716) ÷ 102 = 5.55%. Some APIs scale %B to 85.36 instead of 0.8536 or return bandwidth as 0.0555 instead of 5.55%; field units must therefore be part of validation.

Free technical indicator API options to evaluate

The sources below document indicator endpoints or pre-calculated Bollinger Bands. Treat the table as a verification shortlist, not an endorsement; free access and terms can change.

Bollinger Bands API Python example and validation

Normalize each provider response into one small contract before the indicator reaches a chart or signal engine. The field names below are illustrative; map the provider’s documented schema rather than assuming it already uses these names.

{
  "symbol": "AAPL",
  "interval": "1day",
  "period": 20,
  "deviation": 2,
  "moving_average": "SMA",
  "standard_deviation": "population",
  "adjusted": true,
  "values": [
    {"timestamp": "2026-07-31T20:00:00Z", "upper": "214.83", "middle": "210.10", "lower": "205.37"}
  ]
}

The validator deliberately uses Decimal and timezone-aware timestamps. Supply the API response as payload after handling authentication, HTTP status, rate limits, and provider-specific error objects.

from datetime import datetime
from decimal import Decimal, InvalidOperation


def parse_utc(value: str) -> datetime:
    parsed = datetime.fromisoformat(value.replace("Z", "+00:00"))
    if parsed.tzinfo is None:
        raise ValueError("timestamp must include a timezone")
    return parsed


def validate_bollinger_payload(payload: dict) -> list[dict]:
    required_meta = {
        "symbol", "interval", "period", "deviation",
        "moving_average", "standard_deviation", "adjusted", "values"
    }
    missing = required_meta - payload.keys()
    if missing:
        raise ValueError(f"missing metadata: {sorted(missing)}")
    if int(payload["period"]) < 2 or Decimal(str(payload["deviation"])) <= 0:
        raise ValueError("period and deviation must be positive")

    rows = []
    previous_time = None
    for raw in payload["values"]:
        timestamp = parse_utc(raw["timestamp"])
        try:
            upper = Decimal(str(raw["upper"]))
            middle = Decimal(str(raw["middle"]))
            lower = Decimal(str(raw["lower"]))
        except (KeyError, InvalidOperation) as exc:
            raise ValueError("invalid band row") from exc
        if not upper >= middle >= lower:
            raise ValueError(f"band order failed at {timestamp.isoformat()}")
        if previous_time is not None and timestamp <= previous_time:
            raise ValueError("timestamps must be strictly increasing")
        rows.append({"timestamp": timestamp, "upper": upper,
                     "middle": middle, "lower": lower})
        previous_time = timestamp
    if not rows:
        raise ValueError("response contains no completed indicator rows")
    return rows

How QVeris helps connect Bollinger Bands APIs

• Open the QVeris tool details for technical indicator and market-data capabilities.
• Inspect parameters, outputs, authentication, supported markets, documentation, timestamps, and quotas before connecting.
• Use the QVeris Capability Map to explore adjacent data tools; indicator data is not investment advice.

Free Bollinger Bands API FAQ

External reference links