What Is JSONBIS?
JSONBIS stands for "JSON Bis" — an IETF working group chartered in June 2022 to produce an updated JSON specification that addresses known shortcomings in RFC 8259. "Bis" is IETF convention for a document that revises and obsoletes an existing RFC.
RFC 8259, published in December 2017, is currently the authoritative JSON specification. It is widely implemented and stable. However, the five years since its publication have surfaced several areas where the specification is silent or ambiguous — and where that ambiguity causes real interoperability problems in deployed systems.
Known Gaps in RFC 8259
The JSONBIS charter specifically names the following problem areas that RFC 8259 does not adequately address:
- Number precision: RFC 8259 states that the range and precision of numbers is implementation-specific. It says nothing about how parsers should handle numbers that exceed 64-bit float precision or integer range. This results in silent data corruption in cross-language pipelines.
- Duplicate keys: RFC 8259 says duplicate keys in an object "SHOULD" be avoided but provides no normative guidance on how to handle them when encountered. The word "SHOULD" is non-normative in IETF vocabulary; parsers do what they want.
- Interoperability of extensions: Many applications use JSON-adjacent formats (JSON5, JWCC, JSON with comments) that are not formally specified and create parsing risks when passed to standard parsers.
The Working Group's Mandate
The JSONBIS charter gives the working group a conservative mandate: produce a new RFC that clarifies and tightens RFC 8259 without breaking existing conforming implementations. The goal is not to add new features to JSON but to remove ambiguities that are causing interoperability failures.
The working group operates through the standard IETF process: Internet-Drafts circulated for community review, working group last call, IETF last call, and IESG approval. This process typically takes two to four years for a straightforward specification update.
Expected Outcomes
Based on the charter and early working group discussions, the most likely outcomes are:
- Normative language requiring parsers to signal an error (rather than silently proceeding) when encountering duplicate keys.
- Guidance on number representation — likely recommending that parsers expose the raw string value for numbers that exceed IEEE 754 double precision, allowing applications to handle them with arbitrary precision if needed.
- A clearer definition of what constitutes a conforming JSON parser vs. a conforming JSON generator, separating the two sets of requirements.
The JSONBIS output will not change valid JSON documents — any document valid under RFC 8259 will remain valid. The update tightens parser behaviour, not the data format itself.