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Contributing data

Contributing Your Data with Simmate


This module is intended for the Simmate development team or third-party contributors who wish to integrate their own data. Users should use the load_remote_archive method to access data. For more information, refer to the database documentation.

This module enables the import of data from various databases into Simmate using third-party codes. This data can then be used to build archives that users can access.

Benefits of Integrating Your Data with Simmate

When deciding whether to contribute your database to Simmate, consider the following:

  1. Will you benefit from converting data into a Simmate format?
  2. Will you benefit from distributing an archive? (private or public)

The following sections will provide answers to these questions.

Converting Data into a Simmate Format

Whether your data is open-source or proprietary, the benefits of using Simmate's database module remain the same. It...

  • automatically constructs an API and ORM for your data
  • significantly reduces the file size of your archives

By providing raw data (such as a structure or energy), Simmate will automatically expand your data into the most useful columns, and you can then use our ORM to quickly query data. For example, Simmate can use an energy column/field to create columns for energy_above_hull, formation_energy, decomposes_to, and more -- then you can filter through your data using these new columns. Refer to the "Querying Data" section in the simmate.database module for examples of this query language.

Simmate can efficiently compress your data to a small format by using the concepts of "raw data" vs "secondary columns" (columns that can be quickly recalculated using the raw data). To see just how compact, check out the file sizes for archives of current providers:

Provider Number of Structures Av. Sites per Structure Archive Size
JARVIS 55,712 ~10 8.0 MB
Materials Project 137,885 ~30 45.2 MB
COD 471,664 ~248 1.16 GB
OQMD 1,013,521 ~7 79.2 MB
AFLOW n/a n/a n/a

(Note, COD experiences poor compression because Simmate has not yet optimized storage for disordered structures.)

These small file sizes will make it much easier for downloading and sharing your data. This can have major savings on your database server as well.

Hosting & Distributing the Archive

Here is where being a private vs. open-source provider becomes important. Simmate allows you to decide how others access your data.

If your data can only be accessible to your own team members or subscribers, then you can manage the distribution of the data (via a CDN, dropbox, etc.). Simmate does not require that you distribute your data freely, although we do encourage open-source data. Either way, you can benefit from...

  • reducing the load on your own web APIs

Server load can be reduced because, in Simmate, users download your archive once and then have the data stored locally for as long as they'd like. New users often want to download a large portion of a database (or all of it), and also do so repeatedly as they learn about APIs. Therefore, using Simmate archives upfront can save your team from these large and often-repeated queries.

If you are fine with making your data freely available, you can further benefit by...

  • avoiding the setup of your own server and instead use Simmate's for free
  • exposing your data to the Simmate user base

Providers that permit redistribution are welcome to use our CDN for their archives. This only requires contacting our team and making this request. Further, once your archive is configured, all Simmate users will be able to easily access your data.

How to Integrate Your Data or a New Provider


If you want to avoid this guide, you can just contact our team! Open a github issue to get our attention. In most cases, we only need a CSV or JSON file of your data (in any data format you'd like), and we can handle the rest for you. If you'd like to contribute the data on your own, keep reading.

The end goal for each provider is to allow a user do the following:

from simmate.database import connect
from simmate.database.third_parties import ExampleProviderData


search_results = ExampleProviderData.objects.filter(...).all()
# plus all to_dataframe / to_toolkit features discussed elsewhere

The key part that providers must understand is the load_remote_archive method. This method...

  1. loads an archive of available data (as a zip file from a CDN)
  2. unpacks the data into the Simmate format
  3. saves everything to the user's database (by default this is ~/simmate/database.sqlite3).

This guide serves to make the first step work! Specifically, providers must make the archive that load_remote_archive will load in step 1 and make it downloadable by a CDN or API endpoint. It is up to the provider whether they personally distribute the archive or allow Simmate to distribute it for them.

Outline of Steps

To illustrate how this is done, we will walk through the required steps:

  1. Define a Simmate table
  2. Download data into the Simmate format (i.e. populate the Simmate table)
  3. Compress the data to archive file
  4. Make the archive available via a CDN
  5. Link the CDN to the Simmate table


These steps involve contributing changes to Simmate's code, so we recommend opening a github issue before starting too. That way, our team can help you through this process. If you are new to Github and contributing, be sure to read our tutorial for contributors too.

Step 1: Define a Simmate Table

To host data, Simmate must first know what kind of data you are going to host. We do this by adding a new file to the simmate.database.third_party module. You can view this folder on github here.

Start by defining a DatabaseTable with any custom columns / database mix-ins. You can scroll through the other providers to see how tables are made. Good examples to view are for JARVIS and Materials Project.

Here is a template with useful comments to get you started:

# Start by deciding which base data types you can include. Here, we include a
# crystal structure and an energy, so we use the Structure and Thermodynamics
# mix-ins.
from simmate.database.base_data_types import (

class ExampleProviderData(Structure, Thermodynamics):

    # ----- Table columns + Required settings -----

    # This Meta class tells Simmate where to store the table within our database.
    # All providers with have the exact same thing here. 
    class Meta:
        app_label = "data_explorer"

    # By default, the ID column is an IntegerField, but if your data uses a string
    # like "mp-1234" to denote structures, you can update this column to
    # accept a string instead.
    id = table_column.CharField(max_length=25, primary_key=True)

    # Write the name of your team here!
    source = "The Example Provider Project"

    # We have many alerts to let users know they should cite you. Add the DOI
    # that you'd like them to cite here.
    source_doi = ""

    # If you have any custom fields that you'd like to add, list them off here.
    # All data types supported by Django are also supported by Simmate. You can
    # view those options here:
    custom_column_01 = table_column.FloatField(blank=True, null=True)
    custom_column_02 = table_column.BooleanField(blank=True, null=True)

    # Leave this as None for now. We will update this attribute in a later step.
    remote_archive_link = None

    # ----- Extra optionalfeatures -----

    # (OPTIONAL) Define the "raw data" for your table. This is required if 
    # you'd like to use the `to_archive` method. Fields from the mix-in 
    # will automatically be added.
    archive_fields = [

    # (OPTIONAL) Define how you would like data to be accessible in the REST 
    # API from the website server.
    api_filters = {
        "custom_column_01": ["range"],
        "custom_column_02": ["range"],

    # (OPTIONAL) if you host your data on a separate website, you can specify 
    # how to access that structure here. This is important if you want users
    # to switch to your site for aquiring additional data. 
    def external_link(self) -> str:
        return f"{}"

Before moving on, make sure your table was configured properly by doing the following:

# in the command line
simmate database reset
# in python

from simmate.database import connect
from simmate.database.third_parties import ExampleProviderData

# This will show you all the columns for your table

# this will show you exactly what the table looks like
my_table = ExampleProviderData.objects.to_dataframe()

Step 2: Download Data into the Simmate Format

Now that Simmate knows what to expect, we can load your data into the database. This can be done in several ways. It is entirely up to you which method to use, but here are our recommended options:

  1. JSON or CSV file. If all of your data can be provided via a dump file, then we can use that! This is typically the easiest for a provider's server. For an example of this, see the COD implementation, which uses a download of CIF files.

  2. A custom python package. Feel free to add an optional dependency if your team has already put a lot of work into loading data using a python package. A great example of this is the MPRester class in pymatgen, which we use to pull Material Project data. (JARVIS, AFLOW, OQMD currently use this option too).

  3. REST API or GraphQL. If you have a web API, we can easily pull data using the python requests package. Note, in many cases, a REST API is an inefficient way to pull data - as it involves querying a database thousands of times (once for each page of structures) -- potentially crashing the server. In cases like that, we actually prefer a download file (option 1, shown above).

  4. OPTIMADE endpoint. This is a standardized REST API endpoint that many databases are using now. The huge upside here is that each database will have a matching API -- so once your team has an OPTIMADE endpoint, we can pull data into Simmate with ease. There's no need to build a 2nd implementation. The downside is the same as option 3: OPTIMADE doesn't have a good way to pull data in bulk. Their team is currently working on this though.

  5. Web scraping. As an absolute last resort, we can use requests to scrape webpages for data (or selenium in even more extreme cases.). This requires the most work from our team and is also the least efficient way to grab data. Therefore, scraping should always be avoided if possible.

With your data in hand, you will now add a file that saves data to the local simmate database on your computer. This file can be added to the for_providers module (here). However, if you want your data and its access to remain private, you can also keep this file out of Simmate's source-code. It's up to you, but we encourage providers to host their file in the Simmate repo -- so we can give feedback and so future providers can use it as an example/guide.

Either way, here is a template of how that file will look like:

from django.db import transaction
from rich.progress import track

from simmate.toolkit import Structure
from simmate.database.third_parties import ExampleProviderData

# If you want to use a custom package to load your data, be sure to let our team
# know how to install it.
    from my_package.db import get_my_data
    raise ModuleNotFoundError(
        "You must install my_package with `conda install -c conda-forge my_package`"

# We make this an "atomic transaction", which means if any error is encountered
# while saving results to the database, then the database will be reset to its
# original state. Adding this decorator is optional
def load_all_structures():

    # Use whichever method you chose above to load all of your data!
    # Here' we are pretending to use a function that loads all data into a 
    # python dictionary, but this can vary.
    data = get_my_data()

    # Now iterate through all the data -- which is a list of dictionaries.
    # We use rich.progress.track to monitor progress.
    for entry in track(data):

        # The structure is in the atoms field as a dictionary. We pull this data
        # out and convert it to a toolkit Structure object. Note, this class
        # is currently a subclass of pymatgen.Structure, so it supports reading
        # from different file formats (like CIF or POSCAR) as well.
        structure = Structure(

        # Now that we have a structure object, we can feed that and all
        # other data to the from_toolkit() method. This will create a database
        # object in the Simmate format. Note the data we pass here is based on
        # the ExampleProviderData we defined in the other file.
        structure_db = ExampleProviderData.from_toolkit(
            structure=structure,  # required by Structure mix-in
            energy=entry["my_final_energy"],  # required by Thermodynamics mix-in
            # The get method is useful if not all entries have a given field.

        # and save it to our database!

Try running this on your dataset (or a subset of data if you want to quickly test things). When it finishes, you can ensure data was loaded properly by running:

# in python

from simmate.database import connect
from simmate.database.third_parties import ExampleProviderData

# Check that the number of rows matches your source data.
total_entries = ExampleProviderData.objects.count()

# View the data!
# The [:100] limits this to your first 100 results
my_table = ExampleProviderData.objects.to_dataframe()[:100]

And that's it for writing new code! All that's left is making your data available for others.

Step 3: Compress the Data to Archive File

This will be the easiest step yet. We need to make a zip file for users to download, which can be done in one line:


You'll find a file named (but with the current date) in your working directory. The date is for timestamp and versioning your archives. Because archives are a snapshot of databases that may be dynamically changing/going, this timestamp helps users know which version they are on. You can practice reloading this data into your database too:

  1. Make a copy of your database file in ~/simmate/ so you don't lose your work
  2. In the terminal, reset your database with simmate database reset
  3. In python, try reloading your data with ExampleProviderData.load_archive()
  4. Try viewing your data again with ExampleProviderData.objects.to_dataframe()

Step 4: Make the Archive Available via a CDN

Users will now need the archive file you made to access your data. So you must decide: how should this zip file be downloaded by users?

If you give Simmate approval, we can host your archive file on our own servers. Otherwise you must host your own. The only requirement for your host server is that the zip file can be downloaded from a URL.

While we encourage open-source databases, if you consider your dataset private or commercial, Simmate does not require any payment or involvement for how this CDN is hosted and maintained. Thus, you can manage access to this URL via a subscription or any other method. However, Simmate's CDNs are reserved for archives that are freely distributed.

Note: when uploading new versions of your archive, you should keep the outdated archive either available via its previous URL or, at a minimum, available upon request from users.

In Step 1, we left one attribute as None in our code: remote_archive_link. As a final step, you need to take the URL that you're host your zip file at and paste it here. For example, that line will become:

remote_archive_link = ""

That's it! Let's test out everything again. Note, we are now using load_remote_archive in this process -- which will load your zip file from the URL.

  1. Make a copy of your database file in ~/simmate/ so you don't lose your work
  2. In the terminal, reset your database with simmate database reset
  3. In python, try reloading your data with ExampleProviderData.load_remote_archive()
  4. Try viewing your data again with ExampleProviderData.objects.to_dataframe()

If you've made it this far, thank you for contributing!!! Your data is now easily accessible to all Simmate users, which we hope facilitates its use and even lessen the load on your own servers. Congrats!