C Tested Serializers

Name	Category	Real optimal API (target)	Default build
cJSON	JSON	`cJSON_PrintUnformatted` / `cJSON_Parse`	minimal JSON
yyjson	JSON	`yyjson_mut_write` / `yyjson_read`	minimal JSON
jansson	JSON	`json_dumps` / `json_loads`	minimal JSON (or `-DHAS_JANSSON`)
parson	JSON	`json_serialize_to_string` / `json_parse_string`	minimal JSON
mpack	Binary	`mpack_writer_` / `mpack_tree_`	tagged binary envelope
tinycbor	Binary	`cbor_encoder_` / `cbor_value_`	tagged binary
nanopb	Schema	`pb_encode` / `pb_decode`	field-1 protobuf-style
protobuf-c	Schema	`protobuf_c_message_pack` / `unpack`	tagged binary
flatcc	Schema	`flatcc_builder_*` / verifier	tagged binary
ubj	Binary	`ubjw_` / `ubjr_`	tagged binary
cbor-encode	Binary	`cbor_serialize_alloc` / `cbor_load`	tagged binary
custom-binary	Binary	hand-packed C structs	direct struct dump

Upgrading to real libraries

Vendor sources under c/third_party/ or find_package/pkg-config.
Replace json_write_fixture / write_env in src/register_serializers.c with real API calls.
Keep the serializer_t interface and CSV contract unchanged so analysis stays valid.