diff --git a/case_utils/case_sparql_select/__init__.py b/case_utils/case_sparql_select/__init__.py
index eaa98cb..16d3c67 100644
--- a/case_utils/case_sparql_select/__init__.py
+++ b/case_utils/case_sparql_select/__init__.py
@@ -49,74 +49,44 @@
 _logger = logging.getLogger(os.path.basename(__file__))
 
 
-def main() -> None:
-    parser = argparse.ArgumentParser()
-
-    # Configure debug logging before running parse_args, because there could be an error raised before the construction of the argument parser.
-    logging.basicConfig(
-        level=logging.DEBUG
-        if ("--debug" in sys.argv or "-d" in sys.argv)
-        else logging.INFO
-    )
-
-    parser.add_argument("-d", "--debug", action="store_true")
-    parser.add_argument(
-        "--built-version",
-        choices=tuple(built_version_choices_list),
-        default="case-" + CURRENT_CASE_VERSION,
-        help="Ontology version to use to supplement query, such as for subclass querying.  Does not require networking to use.  Default is most recent CASE release.  Passing 'none' will mean no pre-built CASE ontology versions accompanying this tool will be included in the analysis.",
-    )
-    parser.add_argument(
-        "--disallow-empty-results",
-        action="store_true",
-        help="Raise error if no results are returned for query.",
-    )
-    parser.add_argument(
-        "--use-prefixes",
-        action="store_true",
-        help="Abbreviate node IDs according to graph's encoded prefixes.  (This will use prefixes in the graph, not the query.)",
-    )
-    parser.add_argument(
-        "out_table",
-        help="Expected extensions are .html for HTML tables, .md for Markdown tables, .csv for comma-separated values, and .tsv for tab-separated values.",
-    )
-    parser.add_argument(
-        "in_sparql",
-        help="File containing a SPARQL SELECT query.  Note that prefixes not mapped with a PREFIX statement will be mapped according to their first occurrence among input graphs.",
-    )
-    parser.add_argument("in_graph", nargs="+")
-    args = parser.parse_args()
+def query_text_to_variables(select_query_text: str) -> typing.List[str]:
+    # Build columns list from SELECT line.
+    select_query_text_lines = select_query_text.split("\n")
+    select_line = [
+        line for line in select_query_text_lines if line.startswith("SELECT ")
+    ][0]
+    variables = select_line.replace(" DISTINCT", "").replace("SELECT ", "").split(" ")
+    return variables
 
-    graph = rdflib.Graph()
-    for in_graph_filename in args.in_graph:
-        graph.parse(in_graph_filename)
 
+def graph_and_query_to_data_frame(
+    graph: rdflib.Graph,
+    select_query_text: str,
+    *args: typing.Any,
+    built_version: str = "case-" + CURRENT_CASE_VERSION,
+    disallow_empty_results: bool = False,
+    use_prefixes: bool = False,
+    **kwargs: typing.Any,
+) -> pd.DataFrame:
     # Inherit prefixes defined in input context dictionary.
     nsdict = {k: v for (k, v) in graph.namespace_manager.namespaces()}
 
-    select_query_text = None
-    with open(args.in_sparql, "r") as in_fh:
-        select_query_text = in_fh.read().strip()
-    _logger.debug("select_query_text = %r." % select_query_text)
-
+    # Avoid side-effects on input parameter.
     if "subClassOf" in select_query_text:
-        case_utils.ontology.load_subclass_hierarchy(
-            graph, built_version=args.built_version
-        )
+        _graph = rdflib.Graph()
+        _graph += graph
+        case_utils.ontology.load_subclass_hierarchy(_graph, built_version=built_version)
+    else:
+        _graph = graph
 
-    # Build columns list from SELECT line.
-    select_query_text_lines = select_query_text.split("\n")
-    select_line = [
-        line for line in select_query_text_lines if line.startswith("SELECT ")
-    ][0]
-    variables = select_line.replace(" DISTINCT", "").replace("SELECT ", "").split(" ")
+    variables = query_text_to_variables(select_query_text)
 
     tally = 0
     records = []
     select_query_object = rdflib.plugins.sparql.processor.prepareQuery(
         select_query_text, initNs=nsdict
     )
-    for (row_no, row) in enumerate(graph.query(select_query_object)):
+    for (row_no, row) in enumerate(_graph.query(select_query_object)):
         tally = row_no + 1
         record = []
         for (column_no, column) in enumerate(row):
@@ -131,7 +101,7 @@ def main() -> None:
                 # .decode() is because hexlify returns bytes.
                 column_value = binascii.hexlify(column.toPython()).decode()
             elif isinstance(column, rdflib.URIRef):
-                if args.use_prefixes:
+                if use_prefixes:
                     column_value = graph.namespace_manager.qname(column.toPython())
                 else:
                     column_value = column.toPython()
@@ -141,39 +111,149 @@ def main() -> None:
                 _logger.debug("row[0]column[%d] = %r." % (column_no, column_value))
             record.append(column_value)
         records.append(record)
+
     if tally == 0:
-        if args.disallow_empty_results:
+        if disallow_empty_results:
             raise ValueError("Failed to return any results.")
 
     df = pd.DataFrame(records, columns=variables)
+    return df
 
+
+def data_frame_to_table_text(
+    df: pd.DataFrame,
+    *args: typing.Any,
+    json_indent: typing.Optional[int] = None,
+    json_orient: str,
+    output_mode: str,
+    **kwargs: typing.Any,
+) -> str:
     table_text: typing.Optional[str] = None
-    if args.out_table.endswith(".csv") or args.out_table.endswith(".tsv"):
-        # https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.to_csv.html
+
+    if output_mode in {"csv", "tsv"}:
         sep: str
-        if args.out_table.endswith(".csv"):
+        if output_mode == "csv":
             sep = ","
-        elif args.out_table.endswith(".tsv"):
+        elif output_mode == "tsv":
             sep = "\t"
         else:
             raise NotImplementedError(
                 "Output extension not implemented in CSV-style output."
             )
         table_text = df.to_csv(sep=sep)
-    elif args.out_table.endswith(".html"):
+    elif output_mode == "html":
         # https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.to_html.html
         # Add CSS classes for CASE website Bootstrap support.
         table_text = df.to_html(classes=("table", "table-bordered", "table-condensed"))
-    elif args.out_table.endswith(".md"):
+    elif output_mode == "json":
+        # https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.to_json.html
+
+        table_text = df.to_json(
+            indent=json_indent, orient=json_orient, date_format="iso"
+        )
+    elif output_mode == "md":
         # https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.to_markdown.html
         # https://pypi.org/project/tabulate/
         # Assume Github-flavored Markdown.
+
         table_text = df.to_markdown(tablefmt="github")
-    if table_text is None:
-        raise NotImplementedError(
-            "Unsupported output extension for output filename %r.", args.out_table
-        )
+    else:
+        if table_text is None:
+            raise NotImplementedError("Unimplemented output mode: %r." % output_mode)
+    assert table_text is not None
+
+    return table_text
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
 
+    # Configure debug logging before running parse_args, because there could be an error raised before the construction of the argument parser.
+    logging.basicConfig(
+        level=logging.DEBUG
+        if ("--debug" in sys.argv or "-d" in sys.argv)
+        else logging.INFO
+    )
+
+    parser.add_argument("-d", "--debug", action="store_true")
+    parser.add_argument(
+        "--built-version",
+        choices=tuple(built_version_choices_list),
+        default="case-" + CURRENT_CASE_VERSION,
+        help="Ontology version to use to supplement query, such as for subclass querying.  Does not require networking to use.  Default is most recent CASE release.  Passing 'none' will mean no pre-built CASE ontology versions accompanying this tool will be included in the analysis.",
+    )
+    parser.add_argument(
+        "--disallow-empty-results",
+        action="store_true",
+        help="Raise error if no results are returned for query.",
+    )
+    parser.add_argument(
+        "--json-indent",
+        type=int,
+        help="Number of whitespace characters to use for indentation.  Only applicable for JSON output.",
+    )
+    parser.add_argument(
+        "--json-orient",
+        default="columns",
+        choices=("columns", "index", "records", "split", "table", "values"),
+        help="Orientation to use for Pandas DataFrame JSON output.  Only applicable for JSON output.",
+    )
+    parser.add_argument(
+        "--use-prefixes",
+        action="store_true",
+        help="Abbreviate node IDs according to graph's encoded prefixes.  (This will use prefixes in the graph, not the query.)",
+    )
+    parser.add_argument(
+        "out_table",
+        help="Expected extensions are .html for HTML tables, .json for JSON tables, .md for Markdown tables, .csv for comma-separated values, and .tsv for tab-separated values.  Note that JSON is a Pandas output JSON format (chosen by '--json-orient'), and not JSON-LD.",
+    )
+    parser.add_argument(
+        "in_sparql",
+        help="File containing a SPARQL SELECT query.  Note that prefixes not mapped with a PREFIX statement will be mapped according to their first occurrence among input graphs.",
+    )
+
+    parser.add_argument("in_graph", nargs="+")
+    args = parser.parse_args()
+
+    output_mode: str
+    if args.out_table.endswith(".csv"):
+        output_mode = "csv"
+    elif args.out_table.endswith(".html"):
+        output_mode = "html"
+    elif args.out_table.endswith(".json"):
+        output_mode = "json"
+    elif args.out_table.endswith(".md"):
+        output_mode = "md"
+    elif args.out_table.endswith(".tsv"):
+        output_mode = "tsv"
+    else:
+        raise NotImplementedError("Output file extension not implemented.")
+
+    graph = rdflib.Graph()
+    for in_graph_filename in args.in_graph:
+        graph.parse(in_graph_filename)
+
+    select_query_text: typing.Optional[str] = None
+    with open(args.in_sparql, "r") as in_fh:
+        select_query_text = in_fh.read().strip()
+    if select_query_text is None:
+        raise ValueError("Failed to load query.")
+    _logger.debug("select_query_text = %r." % select_query_text)
+
+    df = graph_and_query_to_data_frame(
+        graph,
+        select_query_text,
+        built_version=args.built_version,
+        disallow_empty_results=args.disallow_empty_results is True,
+        use_prefixes=args.use_prefixes is True,
+    )
+
+    table_text = data_frame_to_table_text(
+        df,
+        json_indent=args.json_indent,
+        json_orient=args.json_orient,
+        output_mode=output_mode,
+    )
     with open(args.out_table, "w") as out_fh:
         out_fh.write(table_text)
         if table_text[-1] != "\n":
diff --git a/tests/case_utils/case_sparql_select/.check-prefixed_results-indented.json b/tests/case_utils/case_sparql_select/.check-prefixed_results-indented.json
new file mode 100644
index 0000000..c356eca
--- /dev/null
+++ b/tests/case_utils/case_sparql_select/.check-prefixed_results-indented.json
@@ -0,0 +1,6 @@
+{
+    "?nFile":{
+        "0":"kb:file-1",
+        "1":"kb:file-2"
+    }
+}
diff --git a/tests/case_utils/case_sparql_select/.check-prefixed_results.json b/tests/case_utils/case_sparql_select/.check-prefixed_results.json
new file mode 100644
index 0000000..63a9d7f
--- /dev/null
+++ b/tests/case_utils/case_sparql_select/.check-prefixed_results.json
@@ -0,0 +1 @@
+{"?nFile":{"0":"kb:file-1","1":"kb:file-2"}}
diff --git a/tests/case_utils/case_sparql_select/.check-w3-output-indented.json b/tests/case_utils/case_sparql_select/.check-w3-output-indented.json
new file mode 100644
index 0000000..8f426c6
--- /dev/null
+++ b/tests/case_utils/case_sparql_select/.check-w3-output-indented.json
@@ -0,0 +1,10 @@
+{
+    "?name":{
+        "0":"Johnny Lee Outlaw",
+        "1":"Peter Goodguy"
+    },
+    "?mbox":{
+        "0":"mailto:jlow@example.com",
+        "1":"mailto:peter@example.org"
+    }
+}
diff --git a/tests/case_utils/case_sparql_select/.check-w3-output.json b/tests/case_utils/case_sparql_select/.check-w3-output.json
new file mode 100644
index 0000000..840035b
--- /dev/null
+++ b/tests/case_utils/case_sparql_select/.check-w3-output.json
@@ -0,0 +1 @@
+{"?name":{"0":"Johnny Lee Outlaw","1":"Peter Goodguy"},"?mbox":{"0":"mailto:jlow@example.com","1":"mailto:peter@example.org"}}
diff --git a/tests/case_utils/case_sparql_select/.gitignore b/tests/case_utils/case_sparql_select/.gitignore
index 9d94989..122f73b 100644
--- a/tests/case_utils/case_sparql_select/.gitignore
+++ b/tests/case_utils/case_sparql_select/.gitignore
@@ -1,3 +1,3 @@
 prefixed*
 subclass-*.md
-w3-output.*
+w3-output*
diff --git a/tests/case_utils/case_sparql_select/Makefile b/tests/case_utils/case_sparql_select/Makefile
index 68f11ec..70bb0ec 100644
--- a/tests/case_utils/case_sparql_select/Makefile
+++ b/tests/case_utils/case_sparql_select/Makefile
@@ -20,12 +20,16 @@ tests_srcdir := $(top_srcdir)/tests
 all: \
   prefixed_results.csv \
   prefixed_results.html \
+  prefixed_results.json \
+  prefixed_results-indented.json \
   prefixed_results.md \
   prefixed_results.tsv \
   subclass-explicit-none.md \
   subclass-implicit-any.md \
   w3-output.csv \
   w3-output.html \
+  w3-output.json \
+  w3-output-indented.json \
   w3-output.md \
   w3-output.tsv
 
@@ -35,6 +39,8 @@ all: \
   check-subclass-implicit-any \
   check-w3-csv \
   check-w3-html \
+  check-w3-json \
+  check-w3-json-indented \
   check-w3-markdown \
   check-w3-tsv
 
@@ -46,6 +52,7 @@ all: \
 check: \
   check-w3-csv \
   check-w3-html \
+  check-w3-json \
   check-w3-markdown \
   check-w3-tsv \
   check-prefixed_results \
@@ -54,6 +61,7 @@ check: \
 check-prefixed_results: \
   check-prefixed_results-csv \
   check-prefixed_results-html \
+  check-prefixed_results-json \
   check-prefixed_results-md \
   check-prefixed_results-tsv
 
@@ -67,6 +75,19 @@ check-prefixed_results-html: \
   prefixed_results.html
 	diff $^
 
+check-prefixed_results-json: \
+  check-prefixed_results-json-indented \
+  .check-prefixed_results.json \
+  prefixed_results.json
+	diff \
+	  .check-prefixed_results.json \
+	  prefixed_results.json
+
+check-prefixed_results-json-indented: \
+  .check-prefixed_results-indented.json \
+  prefixed_results-indented.json
+	diff $^
+
 check-prefixed_results-md: \
   .check-prefixed_results.md \
   prefixed_results.md
@@ -101,6 +122,19 @@ check-w3-html: \
   w3-output.html
 	diff $^
 
+check-w3-json: \
+  .check-w3-output.json \
+  check-w3-json-indented \
+  w3-output.json
+	diff \
+	  .check-w3-output.json \
+	  w3-output.json
+
+check-w3-json-indented: \
+  .check-w3-output-indented.json \
+  w3-output-indented.json
+	diff $^
+
 check-w3-markdown: \
   .check-w3-output.md \
   w3-output.md
@@ -119,6 +153,7 @@ clean:
 	  *.html \
 	  *.md \
 	  *.tsv \
+	  *output*.json \
 	  _*
 
 prefixed_results.%: \
@@ -136,6 +171,22 @@ prefixed_results.%: \
 	    subclass.json
 	mv _$@ $@
 
+prefixed_results-indented.json: \
+  $(tests_srcdir)/.venv.done.log \
+  $(top_srcdir)/case_utils/case_sparql_select/__init__.py \
+  $(top_srcdir)/case_utils/ontology/__init__.py \
+  $(top_srcdir)/case_utils/ontology/version_info.py \
+  subclass.json \
+  subclass.sparql
+	source $(tests_srcdir)/venv/bin/activate \
+	  && case_sparql_select \
+	    --json-indent 4 \
+	    --use-prefixes \
+	    _$@ \
+	    subclass.sparql \
+	    subclass.json
+	mv _$@ $@
+
 subclass-explicit-none.md: \
   $(tests_srcdir)/.venv.done.log \
   $(top_srcdir)/case_utils/case_sparql_select/__init__.py \
@@ -180,3 +231,20 @@ w3-output.%: \
 	    w3-input-2.ttl \
 	    w3-input-3.json
 	mv _$@ $@
+
+w3-output-indented.json: \
+  $(tests_srcdir)/.venv.done.log \
+  $(top_srcdir)/case_utils/case_sparql_select/__init__.py \
+  $(top_srcdir)/case_utils/ontology/__init__.py \
+  $(top_srcdir)/case_utils/ontology/version_info.py \
+  w3-input-1.sparql \
+  w3-input-2.ttl \
+  w3-input-3.json
+	source $(tests_srcdir)/venv/bin/activate \
+	  && case_sparql_select \
+	    --json-indent 4 \
+	    _$@ \
+	    w3-input-1.sparql \
+	    w3-input-2.ttl \
+	    w3-input-3.json
+	mv _$@ $@