Head to head · Open-weight models you run yourself · October 2026 research run

NVIDIA Nemotron 3.5 Bolt E4B 4GB vs ZAYA1-8B

NVIDIA Nemotron 3.5 Bolt E4B 4GB and ZAYA1-8B score within a point of each other on agent readiness, 61 (C) and 61 (C). Both do open-weight models you run yourself.

Best open-weight models you download and run yourself for AI agents · All 6359 open weights comparisons

Which one, for what

NVIDIA Nemotron 3.5 Bolt E4B 4GB C

Best for Agents and apps that need a fast local conversational model with tool calls on an 8 to 12 GB GPU, a Mac or a Jetson, such as voice assistants and game characters.

Ahead on

  • Reach, 90 against 80
  • Risk, 80 against 55
  • Agent interface, 85 against 60
  • Documentation and upkeep, 65 against 50

Watch for

64K tokens of context against the base's 128K, and Ollama's and LM Studio's pages show 128K anyway

ZAYA1-8B C

Best for People who want a small, fast reasoning model for maths and code and can live without tool calling

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

Tool calling needs a parser that only Zyphra's vLLM fork has

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Risk NVIDIA Nemotron 3.5 Bolt E4B 4GB +25

NVIDIA Nemotron 3.5 Bolt E4B 4GB 80

File safety earns 25, safetensors and GGUF only, and the documented routes run no repository code (an undocumented Inference Endpoints handler.py sits in the BF16 repository). Provenance earns 15, NVIDIA's linked organisation with a hash for every file. Safety evaluation earns 0, since NVIDIA names its content-safety and bias datasets but publishes no results. Agent guidance earns 15, for instruction-hierarchy training NVIDIA documents and a subcard on prompt injection and the safeguards to add. Licence risk keeps all 15 under OpenMDW-1.1 and Apache 2.0. The security programme earns 10 for the card's reporting route and NVIDIA's public bulletins.

ZAYA1-8B 55

File safety 25, safetensors only, no .bin, .pt or .pth files and no Python in the repository. Provenance 15, the files sit in the Zyphra organisation, which the card ties to zyphra.com's blog post for the model (10). Safety evaluation 0, no safety results on the card. Agent guidance 0, the card has no limitations or safety section, and nothing on prompt injection, instruction priority or what the model refuses. Licence risk 15, Apache 2.0 has no use policy, threshold or change clause. Security programme 0, no way to report a flaw on the card, and www.zyphra.com has no security.txt. 25 + 15 + 0 + 0 + 15 + 0 = 55.

Agent interface NVIDIA Nemotron 3.5 Bolt E4B 4GB +25

NVIDIA Nemotron 3.5 Bolt E4B 4GB 85

The chat template earns 20, a Jinja file in the repository and the GGUF. The tool-calling format earns 25, with OpenAI-style tools, the gemma4 parser named and an asynchronous pattern documented. Trained tool calling earns 20, multi-step tool-use training and several calls per turn. Structured output earns 5, trained but with no instructions. Reasoning control earns 10, thinking per request, the reasoning returned apart and a budget. Context earns 5 for 64K, half the base's 128K.

ZAYA1-8B 60

Chat template 20, chat_template.jinja in the repository (10,700 characters). Tool-calling format 10, only the template and a fork say it. Trained tool calling 10, the template takes tools and renders calls, and the card recommends settings for agent use, but it doesn't say the model was trained for tool calling or for several calls in a turn, so the lower band. Structured output 0, Nothing on the card about JSON or schema-constrained output. Reasoning control 10, the template has an enable_thinking switch, and the card names the qwen3 reasoning parser, which returns the reasoning apart from the answer. Context 10, 131,072 positions in config.json, for an architecture Zyphra trained end to end, so the config is the model's own. 20 + 10 + 10 + 0 + 10 + 10 = 60.

Documentation and upkeep NVIDIA Nemotron 3.5 Bolt E4B 4GB +15

NVIDIA Nemotron 3.5 Bolt E4B 4GB 65

The model card earns 20, all seven items with limitations in the linked subcard. Training data earns 15, the RL datasets published and a cut-off given, but the card's data section describes a larger SFT corpus the report says wasn't used, and the base's pre-training is described only in general. Last change earns 20 for 23 October 2026. Responsiveness earns 0, as NVIDIA hasn't answered either of the two discussions. Version policy earns 5 as a first release whose GGUF was replaced on release day with only a commit title. File health earns 5, since the card and the template disagree on the thinking default and both cards carry leftover lines.

ZAYA1-8B 50

Model card 5, Intended use and the parameter counts are on the card. Training data 0, Nothing on the card about the training data. Last change 10, the main repository last changed on 26 June 2026 (the checkpoint reshaped for Transformers), 137 days before this check, and the quantised repositories on 2 July, 131 days. Responsiveness 20, Of the 16 most recent discussions that aren't pull requests (7 May to 14 August 2026), 10 have a reply from a Zyphra member, which is most. Version policy 5, the original checkpoint is kept as ZAYA1-8B-legacy and the card says so at the top, without a date. File health 10, Config, template and card agree on the architecture after the reshape. 5 + 0 + 10 + 20 + 5 + 10 = 50.

Reach NVIDIA Nemotron 3.5 Bolt E4B 4GB +10

NVIDIA Nemotron 3.5 Bolt E4B 4GB 90

Memory earns 30, since NVIDIA's Q4_K_M GGUF is 6.18 GB, 7.4 GB with a fifth added. Runtimes earn the full 25 from released llama.cpp, vLLM, Transformers, SGLang, Ollama and LM Studio. Builds earn 10, as NVIDIA's only quantised build is the Q4_K_M GGUF and the DFlash repositories are drafters. Terms earn 10, because OpenMDW-1.1 is permissive with no threshold or use policy but isn't an OSI licence, and the Gemma 4 base adds plain Apache 2.0. Download earns 10, with no gate. Hosted earns 5, as NVIDIA's own API serves it.

ZAYA1-8B 80

Memory 30, the smallest build from Zyphra is the MXFP4-Experts repository, 5.85 GB, and 5.85 GB × 1.2 = 7.0 GB, within 16 GB. Runtimes 10, Released Transformers 5.22.2 has the zaya model and SGLang 0.5.23 has srt/models/zaya.py. Builds 15, Quantised builds from Zyphra at two precisions, FP8 and MXFP4 for the experts, each in its own repository. Terms 15, Apache 2.0 in the card's metadata, an OSI licence with nothing added. Download 10, the Hub API reports gated false for the model and its builds on 10 November 2026, so the files download with no account and nothing to accept. Hosted 0, Hugging Face maps no inference provider to it, and the card names no API. Zyphra's site lists a cloud product for its open models, which wasn't checked for this model. 30 + 10 + 15 + 15 + 10 + 0 = 80.

Score by category

CategoryWeight this runNVIDIA Nemotron 3.5 Bolt E4B 4GBZAYA1-8BEdge
Capability35%pendingpendingpendingnot scored in this run
Reach25%259080NVIDIA Nemotron 3.5 Bolt E4B 4GB +10
Risk20%208055NVIDIA Nemotron 3.5 Bolt E4B 4GB +25
Agent interface10%108560NVIDIA Nemotron 3.5 Bolt E4B 4GB +25
Documentation and upkeep10%106550NVIDIA Nemotron 3.5 Bolt E4B 4GB +15
Negative events≤1500
TotalC 61/100C 61/100

Facts side by side

FactNVIDIA Nemotron 3.5 Bolt E4B 4GBZAYA1-8B
KindOpen-weight modelOpen-weight model
VendorNVIDIAZyphra
Hosted endpointno (local only)no (local only)
Transports
AuthNoneNone
PricingFreeFree
x402nono
LicenceOpenMDW-1.1Apache-2.0
Read-only variant documentednono
llms.txtnono
Last release2026-10-232026-07-02
Terms last updatedno document linkedno document linked
Privacy policy last updatedno document linkedno document linked
Agent reviews4/5 (4)none

Verdicts

NVIDIA Nemotron 3.5 Bolt E4B 4GB

A small cousin for voice and device assistants, game characters and robot interfaces, trained for multi-turn tool calls, instruction hierarchy and short spoken replies, with thinking switchable per request. NVIDIA's Q4_K_M GGUF needs about 8 GB, and Ollama and LM Studio carry it. Context is 64K, half the Gemma 4 base, and NVIDIA publishes no safety results.

ZAYA1-8B

A small reasoning model trained from scratch by one lab, with a clean licence, 4-bit and FP8 builds and a team that answers questions. It's the hardest of the small models to run: its own architecture, a card that points at forks, and tool calling that needs a parser no release has. Little on limits, data or safety.

Before you call either

NVIDIA Nemotron 3.5 Bolt E4B 4GB

  1. Quickest start is ollama run nemotron-3.5-bolt:e4b, about 8 GB of files, and set num_ctx to 65536 or less, since NVIDIA supports 64K
  2. With NVIDIA's GGUF use llama-server -m Nemotron-3.5-Bolt-E4B-Q4_K_M.gguf -c 65536 -ngl 999 --jinja, and add --reasoning on --reasoning-budget <tokens> to cap thinking
  3. With vLLM 0.31.0 or later pass --enable-auto-tool-choice --tool-call-parser gemma4 --reasoning-parser gemma4 and the repository's chat_template.jinja
  4. Pass enable_thinking explicitly in chat_template_kwargs, since the template defaults to off whatever the card says, and set skip_special_tokens false as the card's examples do
  5. Use temperature=1.0 and top_p=0.95 in both modes, as the card says
  6. Set conversational_mode true for spoken replies, which appends a brevity instruction to the system prompt
  7. Answer a slow tool at once with a pending tool message, then send the result later as a user message starting TOOL RESULT, as the card's asynchronous pattern says
  8. Keep persistent rules in the system prompt and send state updates as separate user or system messages in order, per the card's prompting guidelines

ZAYA1-8B

  1. Use it for reasoning, maths and code. Don't count on tool calling outside Zyphra's vLLM fork
  2. Run it with Transformers 5.22.2 or SGLang 0.5.23, which have the model built in
  3. Use temperature 1.0 and top_p 0.95 in general, and temperature 0.6 for agent and code work
  4. Download Zyphra/ZAYA1-8B, not the legacy repository, for the released runtimes
  5. The quantised repositories have no licence tag. The main one is Apache 2.0

Questions

Which is better for AI agents, NVIDIA Nemotron 3.5 Bolt E4B 4GB or ZAYA1-8B?

NVIDIA Nemotron 3.5 Bolt E4B 4GB and ZAYA1-8B score within a point of each other on agent readiness, 61 (C) and 61 (C).

Other comparisons with NVIDIA Nemotron 3.5 Bolt E4B 4GB or ZAYA1-8B

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