What is ERNIE 5.5 Flash Base?
ERNIE 5.5 Flash Base is a pretrained base model from Baidu, released on Hugging Face in October 2026. It is a sparse mixture-of-experts: 280 billion total parameters with about 14 billion active per token, across 43 layers, each MoE layer holding 512 routed experts with the top 10 chosen plus a shared one. It was trained from scratch on 33.5 trillion tokens in mixed FP8, with weights published in both FP8 and BF16.
This is a base model, not a chat model, so it is served through a completions endpoint and has had no instruction tuning or alignment. It handles text only. The maximum context in training was 131,072 tokens (128K); the released config enables up to 1,048,576 (1M) for fine-tuning and inference. The weights carry Baidu's own ERNIE 5.5 Flash Base Model License Agreement, not a standard open-source licence.
Is ERNIE 5.5 Flash Base worth it?
Base models are raw material, not products, and the right readers for this one are teams that train on top of someone else's pretraining. ERNIE 5.5 Flash Base is a good piece of raw material. On Baidu's benchmark table it tops its comparison group, DeepSeek-V4-Flash-Base, Hy3-preview-Base and MiMo-V2.5-Base, on most rows: 93.3 on MMLU against 89.4 for the nearest, 78.4 on MMLU-Pro against 69.2, and strong coding scores for a base model at 82.3 on HumanEval+ and 40.1 on LiveCodeBench.
The efficiency case is the point of the "Flash" name. With 14 billion of its 280 billion parameters active per token, it computes like a 14B model while drawing on a 280B store of knowledge, and the design leans into speed with speculative-decoding features built in. For a team pretraining or continuing training, that ratio is what makes a large model affordable to serve.
Read the scores as Baidu's own, measured against base models Baidu chose. There is no SWE-bench or agentic test here because a base model cannot do those without tuning, and the comparison set is other recent base checkpoints rather than the instruct models most people use day to day.
The catch: two limits narrow who should care. It is text only, and the licence is Baidu's own ERNIE 5.5 Flash Base agreement rather than Apache or MIT, so the usual permissive assumptions do not hold and you must read the terms before building on it. Most readers who just want a capable chat model should look to an instruction-tuned ERNIE or another model entirely.
Our take: if you fine-tune your own models and want a fast, knowledgeable base to start from, this earns a place on the shortlist next to DeepSeek and Qwen bases; if you want something to chat with or call through an API, this is the wrong layer of the stack.
Where it earns its place
A research lab building a domain-specific model
Start from a strong general base instead of pretraining from zero
Fine-tune the BF16 weights on your own corpus; the 14B-active design means training and serving cost closer to a 14B model than a 280B one. Read Baidu's licence first, as it is not a standard open-source one.
An ML team adding a long-context capability
Continue training a base that can stretch to a very long window
The released config enables up to 1,048,576 tokens for fine-tuning and inference, beyond the 131,072 used in pretraining, so you can adapt it for long-document work without changing the base architecture.
An engineer evaluating open base models for cost
Compare knowledge and coding quality per active parameter
Weigh its 93.3 MMLU and 82.3 HumanEval+ against DeepSeek-V4-Flash-Base and Qwen bases at a similar active-parameter budget, remembering these are Baidu's own measurements on base checkpoints.
Before you commit
- Setup
- Weights on Hugging Face in FP8 and BF16; served through a completions endpoint, since there is no chat tuning. Expect to fine-tune before use. The config enables up to a 1M-token context.
- Integrations
- Standard base-model serving and fine-tuning tooling; no instruction, tool-calling or agent features out of the box. Text input and output only.
- Data and privacy
- Open weights under Baidu's ERNIE 5.5 Flash Base Model License Agreement v1.0; running or fine-tuning locally keeps data on your own hardware. The licence is custom, so check its terms before commercial use.
- Cost at scale
- No licence fee, but the cost is the GPU memory and compute for a 280B-parameter MoE; the 14B active per token keeps per-request compute far below the total size.
- Limits
- Base model with no alignment; text only; custom licence rather than Apache or MIT; benchmarks are Baidu's own against base models it selected.
What’s good
- Leads its base-model comparison group on most benchmarks
- 14B active of 280B total keeps serving cost down
- Strong coding scores for a base model (82.3 HumanEval+)
- Weights in both FP8 and BF16; built-in speculative decoding
What’s not
- Base model with no instruction tuning or alignment
- Custom Baidu licence, not Apache or MIT
- Text only; no vision or agentic use
- All benchmarks run by Baidu against chosen base models
Best for
Teams that pretrain or fine-tune their own models and want a fast, knowledgeable mixture-of-experts base rather than a ready-to-use chat model.
ERNIE 5.5 Flash Base alternatives
ERNIE 5.5 Flash Base: common questions
- Is ERNIE 5.5 Flash Base worth it?
- A strong pretrained base model that leads its class on Baidu's own table, useful mainly to teams who fine-tune their own models rather than call an API. We rate it 4.0 out of 5.
- How much does ERNIE 5.5 Flash Base cost?
- Free weights under Baidu's custom ERNIE 5.5 Flash Base licence. No hosted price for the base model; you pay the GPU to run or fine-tune it.
- What are the downsides of ERNIE 5.5 Flash Base?
- Base model with no instruction tuning or alignment; custom Baidu licence, not Apache or MIT; text only; no vision or agentic use; all benchmarks run by Baidu against chosen base models.
- Who is ERNIE 5.5 Flash Base best for?
- Teams that pretrain or fine-tune their own models and want a fast, knowledgeable mixture-of-experts base rather than a ready-to-use chat model.
- How much does ERNIE 5.5 Flash Base cost for a team or in production?
- No licence fee, but the cost is the GPU memory and compute for a 280B-parameter MoE; the 14B active per token keeps per-request compute far below the total size.
- Is ERNIE 5.5 Flash Base safe for company data?
- Open weights under Baidu's ERNIE 5.5 Flash Base Model License Agreement v1.0; running or fine-tuning locally keeps data on your own hardware. The licence is custom, so check its terms before commercial use.
- What are the best ERNIE 5.5 Flash Base alternatives?
- The closest alternatives we have reviewed are ERNIE 5.1, DeepSeek-V4.1-Flash and Qwen3.6.
Answers checked Nov 14, 2026.
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