.. _sphx_glr_api_gallery_contracts_tokens:

Token standards
---------------

Fungible and non-fungible tokens, and the races and traps in their interfaces.


.. raw:: html

  <div id='sg-tag-list' class='sphx-glr-tag-list'></div>


.. raw:: html

    <div class="sphx-glr-thumbnails">

.. thumbnail-parent-div-open

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    <div class="sphx-glr-thumbcontainer" tooltip="Fabian Vogelsteller and Vitalik Buterin&#x27;s ERC-20 gave fungible tokens one interface: transfer, balanceOf, and a two-step delegation, where approve(spender, n) lets a spender move up to n tokens with transferFrom. Any wallet or exchange can then handle any token.">

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  .. image:: /api/gallery/contracts/tokens/images/thumb/sphx_glr_plot_01_erc20_approve_race_thumb.png
    :alt:

  :doc:`/api/gallery/contracts/tokens/plot_01_erc20_approve_race`

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      <div class="sphx-glr-thumbnail-title">ERC-20 tokens and the approve/transferFrom race (2015)</div>
    </div>


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    <div class="sphx-glr-thumbcontainer" tooltip="ERC-721, by William Entriken, Dieter Shirley, Jacob Evans and Nastassia Sachs, gave each token an identity: a mapping from token ids to owners,">

.. only:: html

  .. image:: /api/gallery/contracts/tokens/images/thumb/sphx_glr_plot_02_erc721_safe_transfers_thumb.png
    :alt:

  :doc:`/api/gallery/contracts/tokens/plot_02_erc721_safe_transfers`

.. raw:: html

      <div class="sphx-glr-thumbnail-title">ERC-721 non-fungible tokens and safe transfers (2018)</div>
    </div>


.. thumbnail-parent-div-close

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    </div>


.. toctree::
   :hidden:

   /api/gallery/contracts/tokens/plot_01_erc20_approve_race
   /api/gallery/contracts/tokens/plot_02_erc721_safe_transfers