diff --git a/server/cli/launch.py b/server/cli/launch.py
index db50ed4c..ca2a0e97 100644
--- a/server/cli/launch.py
+++ b/server/cli/launch.py
@@ -337,10 +337,6 @@ def launch(
     handle_verbose(verbose)
     handle_scripts(scripts)
 
-    if not title and datapath is not None:
-        file_parts = splitext(basename(datapath))
-        title = file_parts[0]
-
     if port:
         if debug:
             raise click.ClickException("--port and --debug may not be used together (try --verbose for error logging).")
diff --git a/server/common/app_config.py b/server/common/app_config.py
index 47d8d5a5..854a18f7 100644
--- a/server/common/app_config.py
+++ b/server/common/app_config.py
@@ -1,7 +1,6 @@
 # -*- coding: utf-8 -*-
 
 from server import __version__ as cellxgene_version
-from os.path import basename, splitext
 
 
 class AppFeature(object):
@@ -64,21 +63,10 @@ class AppConfig(object):
                 raise RuntimeError(f"unknown config parameter {k}.")
 
     def get_title(self, data_adaptor):
-        if self.title:
-            return self.title
-
-        # TODO:  find a place to stash the dataset title, such as a
-        # json file at the same location as the data matrix.
-        # for example, if the dataset is at abc.cxg then a file with
-        # the title and about info could be at abc.cxg.metadata.
-        # for now just return the basename
-        location = data_adaptor.get_location()
-        if location.endswith("/"):
-            location = location[:-1]
-        return splitext(basename(location))[0]
+        return self.title if self.title else data_adaptor.get_title()
 
     def get_about(self, data_adaptor):
-        return self.about
+        return self.about if self.about else data_adaptor.get_about()
 
     def get_config(self, data_adaptor, annotation=None):
 
diff --git a/server/common/rest.py b/server/common/rest.py
index 4516f111..d5792c97 100644
--- a/server/common/rest.py
+++ b/server/common/rest.py
@@ -36,7 +36,7 @@ def schema_get(data_adaptor, annotations):
 
 def config_get(app_config, data_adaptor, annotations):
     config = app_config.get_config(data_adaptor, annotations)
-    return make_response(make_response(jsonify(config), HTTPStatus.OK))
+    return make_response(jsonify(config), HTTPStatus.OK)
 
 
 def annotations_obs_get(request, data_adaptor, annotations):
diff --git a/server/converters/cxgtool.py b/server/converters/cxgtool.py
new file mode 100644
index 00000000..9015525c
--- /dev/null
+++ b/server/converters/cxgtool.py
@@ -0,0 +1,389 @@
+"""
+This program converts an [AnnData H5AD](https://anndata.readthedocs.io/en/stable/)
+into a cellxgene TileDB structure, aka a 'CXG'.
+
+The organization of the TileDB structure is:
+
+    the.cxg                 TileDB Group
+    |-- obs                 TileDB array containing cell (row) attributes, one attribute per
+    |                       dataframe columm, shape (n_obs,)
+    |-- var                 TileDB array containing gene (column) attributes, with one attribute per
+    |                       dataframe column, shape (n_var,)
+    |-- X                   Main count matrix as a 2D TileDB array, single unnanmed numeric attribute
+    |-- emb                 TileDB group, storing optional embeddings (group may be empty)
+    |   |-- <name1>         TileDB Array, single anon attribute, ND numeric array, shape (n_obs, N)
+    |-- cxg_group_metadata  Empty array used only to stash metadata about the overall object.
+    ...
+
+All arrays are defined to have a uint32 domain, zero based.  All X counds and embedding
+coordinates are coerced to float32, which is ample precision for visualization purposes.
+Dataframe (metadata) types are generally preserved, or where that is not possible,
+converted to somemthing with equal representative value in the cellxgene application
+(eg, categorical types are converted to string, bools to uint8, etc).
+
+The following objects are also decorated with auxilliary metadata using TileDB
+array metadata:
+
+* cxg_group_metadata: minimally, will contain a 'cxg_version' field, which
+  is a semver string identifing the version number of the CXG layout.
+  It may also contain 'cxg_parameters', a JSON-encoded parameter list
+  describing CXG-wide dataset parameters.
+
+* obs, var: both contain an optional 'cxg_schema' field that is a json string,
+  containing per-column (attribute) schema hinting.  This is used where the TileDB
+  native typing information is insufficient to reconstruct useful information
+  such as categorical typing from Pandas DataFrames, and to communicate which column
+  is the preferred human-readable index for obs & var.
+
+This file also embodies a number of empirically derived tiledb schema parameters,
+including the global data layout, spatial tile size, and the like. The CXG is
+self-describing in these areas, and the actual values (eg, tile size) are empirically
+derived from benchmarking. They may change in the future.
+
+---
+
+TODO/ISSUES:
+* add sub-command structure to argparse, for future sub-commands
+* Possible future work: accept Loom files
+
+"""
+import anndata
+import tiledb
+import argparse
+import numpy as np
+import pandas as pd
+from os.path import splitext, basename
+import json
+
+
+# the CXG container version number.  Must be a semver string.
+CXG_VERSION = "0.1"
+
+
+def log(level, *args):
+    global log_level
+    if log_level and level <= log_level:
+        print(*args)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("h5ad", nargs="?", help="H5AD file name")
+    parser.add_argument(
+        "--backed", action="store_true", help="loaded in file backed mode. Will be slower, but use less memory."
+    )
+    parser.add_argument(
+        "--obs-names", help="Name of annotation to use for observations. If not specified, will use the obs index."
+    )
+    parser.add_argument(
+        "--var-names", help="Name of annotation to use for variables. If not specified, will use the var index."
+    )
+    parser.add_argument("--verbose", "-v", action="count", default=0, help="verbose output")
+    parser.add_argument("--title", help="Human readable dataset title.  If omitted, will use filename")
+    parser.add_argument(
+        "--about",
+        metavar="<URL>",
+        help="URL providing more information about the dataset (hint: must be a fully specified absolute URL).",
+    )
+    parser.add_argument("--out", "-o", help="output CXG file name")
+    args = parser.parse_args()
+
+    global log_level
+    log_level = args.verbose
+
+    adata = anndata.read_h5ad(args.h5ad, backed="r" if args.backed else None)
+    log(1, f"{basename(args.h5ad)} loaded...")
+
+    basefname = splitext(basename(args.h5ad))[0]
+    out = args.out if args.out is not None else basefname
+    container = out if splitext(out)[1] == ".cxg" else out + ".cxg"
+    title = args.title if args.title is not None else basefname
+
+    write_cxg(adata, container, title, var_names=args.var_names, obs_names=args.obs_names, about=args.about)
+
+    log(1, "done")
+
+
+def write_cxg(adata, container, title, var_names=None, obs_names=None, about=None):
+    if not adata.var.index.is_unique:
+        raise ValueError("Variable index is not unique - unable to convert.")
+    if not adata.obs.index.is_unique:
+        raise ValueError("Observation index is not unique - unable to convert.")
+
+    ctx = tiledb.Ctx(
+        {
+            "sm.num_reader_threads": 32,
+            "sm.num_writer_threads": 32,
+            "sm.consolidation.buffer_size": 1 * 1024 * 1024 * 1024,
+        }
+    )
+
+    tiledb.group_create(container, ctx=ctx)
+    log(1, f"\t...group created, with name {container}")
+
+    # dataset metadata
+    save_metadata(container, {"title": title, "about": about})
+    log(1, "\t...dataset metadata saved")
+
+    # var/gene dataframe
+    save_dataframe(container, "var", adata.var, var_names, ctx=ctx)
+    log(1, "\t...var dataframe created")
+
+    # obs/cell dataframe
+    save_dataframe(container, "obs", adata.obs, obs_names, ctx=ctx)
+    log(1, "\t...obs dataframe created")
+
+    # embeddings
+    e_container = f"{container}/emb"
+    tiledb.group_create(e_container, ctx=ctx)
+    save_embeddings(e_container, adata, ctx)
+    log(1, "\t...embeddings created")
+
+    # X matrix
+    save_X(container, adata, ctx)
+    log(1, "\t...X created")
+
+
+def _can_cast_to_float32(col):
+    if col.dtype.kind == "f":
+        # force downcast for all floats
+        return True
+    return False
+
+
+def _can_cast_to_int32(col):
+    if col.dtype.kind in ["i", "u"]:
+        if np.can_cast(col.dtype, np.int32):
+            return True
+        ii32 = np.iinfo(np.int32)
+        if col.min() >= ii32.min and col.max() <= ii32.max:
+            return True
+    return False
+
+
+def cxg_type(col):
+    """ given a dtype, return an encoding dtype and any schema hints """
+    dtype = col.dtype
+    kind = dtype.kind
+    if _can_cast_to_float32(col):
+        return (np.float32, {})
+    elif _can_cast_to_int32(col):
+        return (np.int32, {})
+    elif dtype == np.bool_ or dtype == np.bool:
+        return (np.uint8, {type: "boolean"})
+    elif kind == "O" and isinstance(dtype, pd.CategoricalDtype):
+        typ, hint = cxg_type(dtype.categories)
+        hint["categories"] = dtype.categories.tolist()
+        return (typ, hint)
+    elif kind == "O":
+        return (np.unicode, {"type": "string"})
+    else:
+        raise TypeError(f"Annotations of type {dtype} are unsupported by cellxgene.")
+
+
+def cxg_dtype(col):
+    return cxg_type(col)[0]
+
+
+def create_dataframe(name, df, ctx):
+    """
+    Current access patterns are oriented toward reading very large slices of
+    the dataframe, one attribute at a time.  Attribute data also tends to be
+    (often) repetitive (bools, categories, strings).
+    Given this, we use:
+    * a large tile size (1000)
+    * very aggressive compression levels
+    """
+    filter = tiledb.FilterList(
+        [
+            # attempt aggressive compression as many of these dataframes are very repetitive
+            # strings, bools and other non-float data.
+            tiledb.ZstdFilter(level=22),
+        ]
+    )
+    attrs = [tiledb.Attr(name=col, dtype=cxg_dtype(df[col]), filters=filter) for col in df]
+    domain = tiledb.Domain(tiledb.Dim(domain=(0, df.shape[0] - 1), tile=min(df.shape[0], 1000), dtype=np.uint32))
+    schema = tiledb.ArraySchema(
+        domain=domain, sparse=False, attrs=attrs, cell_order="row-major", tile_order="row-major"
+    )
+    tiledb.DenseArray.create(name, schema)
+
+
+def create_unique_column_name(df_cols, col_name_prefix):
+    """
+    given the columns of a dataframe, and a name prefix, return a column name which
+    does not exist in the dataframe, AND which is prefixed by `prefix`
+
+    The approach is to append a numeric suffix, starting at zero and increasing by
+    one, until an unused name is found (eg, prefix_0, prefix_1, ...).
+    """
+    suffix = 0
+    while f"{col_name_prefix}{suffix}" in df_cols:
+        suffix += 1
+    return f"{col_name_prefix}{suffix}"
+
+
+def alias_index_col(df, df_name, index_col_name):
+    """
+    We rely in the existance of a unique, human-readable index for
+    any dataframe (eg, var is typically gene name, obs the cell name).
+    The user can specify these via the --obs-names and --var-names config.
+    If they are not specified, use the existing index to create them, giving
+    the resulting column a unique name (eg, "name").
+
+    In both cases, enforce that the result is unique, and communicate the
+    index column name via the 'index' field in the schema hints.
+    """
+    if index_col_name is None:
+        if not df.index.is_unique:
+            raise KeyError(
+                f"Values in {df_name}.index must be unique. "
+                "Please prepare data to contain unique index values, or specify an "
+                "alternative with --{ax_name}-name."
+            )
+        index_col_name = create_unique_column_name(df.columns, "name_")
+        # turn the index into a normal column
+        df.rename_axis(index_col_name, inplace=True)
+        df.reset_index(inplace=True)
+
+    elif index_col_name in df.columns:
+        # User has specified alternative column for unique names, and it exists
+        if not df[index_col_name].is_unique:
+            raise KeyError(
+                f"Values in {df_name}.{index_col_name} must be unique. Please prepare data to contain unique values."
+            )
+
+    else:
+        raise KeyError(f"Annotation {index_col_name}, specified in --{df_name}-name, does not exist.")
+
+    return (df, index_col_name)
+
+
+def save_dataframe(container, name, df, index_col_name, ctx):
+    A_name = f"{container}/{name}"
+    (df, index_col_name) = alias_index_col(df, name, index_col_name)
+    create_dataframe(A_name, df, ctx=ctx)
+    with tiledb.DenseArray(A_name, mode="w", ctx=ctx) as A:
+        value = {}
+        schema_hints = {}
+        for k, v in df.items():
+            dtype, hints = cxg_type(v)
+            value[k] = v.to_numpy(dtype=dtype)
+            if hints:
+                schema_hints.update({k: hints})
+
+        schema_hints.update({"index": index_col_name})
+        A[:] = value
+        A.meta["cxg_schema"] = json.dumps(schema_hints)
+
+    tiledb.consolidate(A_name, ctx=ctx)
+
+
+def create_emb(e_name, emb):
+    """
+    Embeddings are typically accessed with very large slices (or all of the embedding),
+    and do not benefit from overly aggressive compression due to their format.  Given
+    this, we use:
+    * large tile size (1000)
+    * default compression level
+    """
+    filters = tiledb.FilterList([tiledb.ZstdFilter(), ])
+    attrs = [tiledb.Attr(dtype=emb.dtype, filters=filters)]
+    dims = []
+    for d in range(emb.ndim):
+        shape = emb.shape
+        dims.append(tiledb.Dim("", domain=(0, shape[d] - 1), tile=min(shape[d], 1000), dtype=np.uint32))
+    domain = tiledb.Domain(*dims)
+    schema = tiledb.ArraySchema(
+        domain=domain, sparse=False, attrs=attrs, capacity=1_000_000, cell_order="row-major", tile_order="row-major"
+    )
+    tiledb.DenseArray.create(e_name, schema)
+
+
+def is_valid_embedding(adata, name, arr):
+    """ return True if this layout data is a valid array for front-end presentation:
+        * ndarray, with shape (n_obs, >= 2), dtype float/int/uint
+        * contains only finite values
+        * follows ScanPy embedding naming conventions
+    """
+    is_valid = type(name) == str and name.startswith("X_") and len(name) > 2
+    is_valid = is_valid and type(arr) == np.ndarray and arr.dtype.kind in "fiu"
+    is_valid = is_valid and arr.shape[0] == adata.n_obs and arr.shape[1] >= 2
+    is_valid = is_valid and np.all(np.isfinite(arr))
+    return is_valid
+
+
+def save_embeddings(container, adata, ctx):
+    for (name, value) in adata.obsm.items():
+        if is_valid_embedding(adata, name, value):
+            e_name = f"{container}/{name[2:]}"
+            create_emb(e_name, value)
+            with tiledb.DenseArray(e_name, mode="w", ctx=ctx) as A:
+                A[:] = value
+            log(1, f"\t\t...{name} embedding created")
+        tiledb.consolidate(e_name, ctx=ctx)
+
+
+def create_X(X_name, shape):
+    """
+    Dense, always.  Future task: explore if sparse encoding is worth the trouble
+    below a sparsity threshold.
+
+    The X matrix is access in both row and column oriented patterns, depending on the
+    particular operation.  Because of the data type, default compression works best.
+    The tile size (50, 100) and global layout (row/col) was choosen empirically, by benchmarking
+    the current cellxgene backend.
+    """
+    filters = tiledb.FilterList([tiledb.ZstdFilter()])
+    attrs = [tiledb.Attr(dtype=np.float32, filters=filters)]
+    domain = tiledb.Domain(
+        tiledb.Dim(name="obs", domain=(0, shape[0] - 1), tile=min(shape[0], 50), dtype=np.uint32),
+        tiledb.Dim(name="var", domain=(0, shape[1] - 1), tile=min(shape[1], 100), dtype=np.uint32),
+    )
+    schema = tiledb.ArraySchema(
+        domain=domain, sparse=False, attrs=attrs, cell_order="row-major", tile_order="col-major"
+    )
+    tiledb.DenseArray.create(X_name, schema)
+
+
+def save_X(container, adata, ctx):
+    # Save X count matrix
+    X_name = f"{container}/X"
+    shape = adata.X.shape
+    create_X(X_name, shape)
+
+    stride = min(int(np.power(10, np.around(np.log10(1e9 / shape[1])))), 10_000)
+    with tiledb.DenseArray(X_name, mode="w", ctx=ctx) as X:
+        for row in range(0, shape[0], stride):
+            lim = min(row + stride, shape[0])
+            a = adata.X[row:lim, :]
+            if type(a) is not np.ndarray:
+                a = a.toarray()
+            X[row:lim, :] = a
+            log(2, "\t...rows", row, "to", lim)
+        tiledb.consolidate(X_name, ctx=ctx)
+
+    tiledb.consolidate(X_name, ctx=ctx)
+
+
+def save_metadata(container, metadata):
+    """
+    Save all dataset-wide metadata.   This includes:
+    * CXG version
+    * dataset metadata, such as title and about link.
+
+    Longer term, tiledb will have support for metadata on groups. Until
+    such feature exists, create an empty array and annotate that array.
+
+    https://github.com/TileDB-Inc/TileDB-Py/issues/254
+    """
+    a_name = f"{container}/cxg_group_metadata"
+    with tiledb.from_numpy(a_name, np.zeros((1,))) as A:
+        pass
+    with tiledb.DenseArray(a_name, mode="w") as A:
+        A.meta["cxg_version"] = CXG_VERSION
+        A.meta["cxg_properties"] = json.dumps(metadata)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/server/data_common/data_adaptor.py b/server/data_common/data_adaptor.py
index 109b1962..4bc2a5d1 100644
--- a/server/data_common/data_adaptor.py
+++ b/server/data_common/data_adaptor.py
@@ -2,6 +2,8 @@ from abc import ABCMeta, abstractmethod
 from server_timing import Timing as ServerTiming
 import numpy as np
 import pandas as pd
+from os.path import basename, splitext
+
 from server.data_common.fbs.matrix import encode_matrix_fbs
 from server.common.constants import Axis, DEFAULT_TOP_N
 from server.common.errors import FilterError, JSONEncodingValueError
@@ -97,6 +99,16 @@ class DataAdaptor(metaclass=ABCMeta):
     def get_location(self):
         pass
 
+    def get_about(self):
+        return None
+
+    def get_title(self):
+        # default to file name
+        location = self.get_location()
+        if location.endswith("/"):
+            location = location[:-1]
+        return splitext(basename(location))[0]
+
     @abstractmethod
     def get_schema(self):
         """
diff --git a/server/data_cxg/cxg_adaptor.py b/server/data_cxg/cxg_adaptor.py
index c51aceec..7d6da9f6 100644
--- a/server/data_cxg/cxg_adaptor.py
+++ b/server/data_cxg/cxg_adaptor.py
@@ -52,11 +52,17 @@ class CxgAdaptor(DataAdaptor):
     def open(location, args):
         return CxgAdaptor(location, args)
 
+    def get_about(self):
+        return self.about if self.about else super().get_about()
+
+    def get_title(self):
+        return self.title if self.title else super().get_title()
+
     def get_location(self):
         return self.url
 
     def get_name(self):
-        return "cellxgene cxcxgg adaptor version"
+        return "cellxgene cxg adaptor version"
 
     def get_library_versions(self):
         return dict(tiledb=tiledb.__version__)
@@ -107,8 +113,40 @@ class CxgAdaptor(DataAdaptor):
         return True
 
     def _validate_and_initialize(self):
-        if not self.isvalid(self.url):
-            raise DatasetAccessError(f"invalid cxg dataset {self.url}")
+        """
+        remember, preload_validation() has already been called, so
+        no need to repeat anything it has done.
+
+        Load the CXG "group" metadata and cache instance values.
+        Be very aware of multiple versions of the CXG object.
+
+        CXG versions in the wild:
+        * version 0, aka "no version" -- can be detected by the lack
+          of a cxg_group_metadata array.
+        * version 0.1 -- metadata attache to cxg_group_metadata array.
+          Same as 0, except it adds group metadata.
+        """
+        a_type = tiledb.object_type(path_join(self.url, "cxg_group_metadata"))
+        if a_type is None:
+            # version 0
+            cxg_version = "0.0"
+            title = None
+            about = None
+        elif a_type == "array":
+            # version >0
+            gmd = self.open_array("cxg_group_metadata")
+            cxg_version = gmd.meta['cxg_version']
+            if cxg_version == "0.1":
+                cxg_properties = json.loads(gmd.meta['cxg_properties'])
+                title = cxg_properties.get('title', None)
+                about = cxg_properties.get('about', None)
+
+        if cxg_version not in ['0.0', '0.1']:
+            raise DatasetAccessError(f"cxg matrix is not valid: {self.url}")
+
+        self.title = title
+        self.about = about
+        self.cxg_version = cxg_version
 
     def open_array(self, name):
         try: