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Our API uses consistent formats for dates and numeric values. The field definition in the API reference remains the source of truth for a field’s type, precision, and constraints.

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Dates and times

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Dates

We represent calendar dates as ISO 8601 strings in YYYY-MM-DD format:
A date identifies a calendar day. It does not include a time or time zone.

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Timestamps

We represent timestamps as ISO 8601 strings. Include a UTC designator (Z) or an explicit UTC offset when you send a timestamp that identifies an instant:
The following values identify the same instant:
Fractional seconds are optional unless an endpoint states otherwise. We recommend sending timestamps in UTC and retaining the time zone from values returned by our API.
Don’t send a local timestamp without a time zone for fields that identify an instant. Some endpoints require an offset and will reject an ambiguous value such as 2026-07-14T08:36:12.
When you use a positive UTC offset in a query parameter, URL-encode the + as %2B. For example, send 2026-07-14T10:36:12%2B02:00.

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Numbers

We encode decimal values as JSON strings so their exact value survives serialization across programming languages:
Use a period (.) as the decimal separator. Don’t include thousands separators or currency symbols. The required precision depends on the field. Common formats include: Some fields allow a different precision, so check the endpoint schema before validating or rounding a value. Integer fields, such as a year or count, remain JSON numbers.
Some request schemas also accept JSON numbers for decimal fields. We recommend sending decimal strings to avoid binary floating-point rounding before the request reaches our API. Use a decimal type such as Java’s BigDecimal, Python’s Decimal, or Swift’s Decimal when you calculate these values.

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Percentages and rates

Percentage-related fields use either decimal fractions or percentage-point values. Check the field description to determine which representation applies.

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Decimal fractions

Returns, ratios, allocation weights, and buffers are generally decimal fractions. Multiply the API value by 100 when displaying it as a percentage: For example, an expense_ratio of "0.0020" means 0.20%, and a return of "0.0925" means 9.25%.

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Percentage-point values

Some fields follow financial-market or business conventions and contain the displayed percentage directly: Don’t infer the representation from a field name alone. For example, gross_unrealized_percentage is a decimal fraction, while ownership_percentage is a percentage-point value. The endpoint’s field description identifies the expected form.